2024年12月, 優秀賞, 不均一系亜鉛(II)錯体触媒によるエチレンオキシド類と二酸化炭素の環化付加反応
安田 翔;藤澤清史

2021年12月, 優秀ポスター賞, 多座配位子によるMn(Ⅱ)錯体の合成と酸化剤との反応, 日本化学会関東支部長
五十木理子
国内学会・会議・シンポジウム等の賞

2016年11月, 優秀ポスター賞, 低配位N2型配位子を用いた鉄ニトロシル錯体の合成, 日本化学会関東支部長
栗原遥香
国内学会・会議・シンポジウム等の賞

2015年11月, 優秀ポスター賞, 四配位鉄ニトロシル錯体の合成と反応性の検討, 日本化学会関東支部長
相馬翔子
国内学会・会議・シンポジウム等の賞

2015年10月, Outstanding Reviewer, ChemPubSoc Europe、Asian Chemical Editorial Society (ACES)
学会誌・学術雑誌による顕彰

2011年08月, 先端錯体工学研究会賞, 遷移金属イオンの特性を利用した不活性小分子の活性化に関する研究, 先端錯体化学研究会

Blue copper protein model compounds containing stable Cu–S bond: structure, properties, and function　　　　　　　　　　　　　　　
Kiyoshi Fujisawa; Robert K. Szilagyi, 筆頭著者
Copper in Biology from Molecular Structures to Cellular Processes and Living Systems; Coordination Chemistry Perspectives, 2025年06月, ［査読有り］, ［招待有り］

〔主要な業績〕Crystal structure of 4-[3,5-bis(propan-2-yl)-1H-pyrazol-4-yl]pyridine, C14H19N3
Harukaze Kanazawa; Edward R. T. Tiekink; Kiyoshi Fujisawa, ラスト(シニア)オーサー, De Gruyter, Berlin/Boston,NCRS-2022-0362
Zeitschrift für Kristallographie - New Crystal Structures, 2025年03月12日, ［査読有り］

Crystal structure of bromido[hydridotris(3-tert-butyl-5-isopropylpyrazolyl)borato-κ3 N,N′,N″]copper(II), C30H52BBrCuN6
Kiyoshi Fujisawa; Edward R.T. Tiekink, 筆頭著者
Zeitschrift für Kristallographie - New Crystal Structures, 2025年03月11日, ［査読有り］

Crystal structure of chlorido{hydridotris[3-mesityl-5-methyl-1H-pyrazol-1-yl-κN3]borato}-copper(II) dichloromethane monosolvate
Kiyoshi Fujisawa; Edward R. T. Tiekink, 筆頭著者
Zeitschrift für Kristallographie - New Crystal Structures, 2025年03月11日, ［査読有り］

Crystal structure of 3,5-bis(t-butyl)-1H-pyrazol-4-amine, C11H21N3
Kiyoshi Fujisawa; Shuto Sugihara; Edward R. T. Tiekink, 筆頭著者
Zeitschrift für Kristallographie - New Crystal Structures, 2025年03月07日, ［査読有り］

Coordination chemistry of 4-aminopyrazole: Structure and physicochemical properties of cobalt(II) chlorido complexes, and amino group reactivity towards a ketone to yield an imine bond
Kiyoshi Fujisawa; Keigo Ageishi; Kako Iwai; Mitsuki Okano; Robby Y. Williams-Sekiguchi; Edward R.T. Tiekink, 筆頭著者, Elsevier BV
Inorganica Chimica Acta, 2024年07月24日, ［査読有り］

〔主要な業績〕Crystal structure of bis(3,5-diisopropyl-1H-pyrazol-4-ammonium) tetrafluoroterephthalate, 2[C9H18N3][C8F4O4]
Kiyoshi Fujisawa; Seigo Harakuni; Kako Iwai; Keigo Ageishi; Edward R. T. Tiekink, 筆頭著者, De Gruyter, Berlin/Boston,NCRS-2023-0455
Zeitschrift für Kristallographie - New Crystal Structures, 2024年04月25日, ［査読有り］

〔主要な業績〕Crystal structure of [N(E),N′(E)]-N,N′-(1,4-phenylenedimethylidyne)bis-3,5-bis(propan-2-yl)-1H-pyrazol-4-amine, C26H36N6
Kiyoshi Fujisawa; Keigo Ageishi; Edward R. T. Tiekink, 筆頭著者, De Gruyter, Berlin/Boston,NCRS-2023-0305
Zeitschrift für Kristallographie - New Crystal Structures, 2023年10月26日, ［査読有り］

〔主要な業績〕Crystal structure of bis(3,5-dimethyl-1H-pyrazol-4-ammonium) tetrafluoroterephthate, 2[C5H10N3][C8F4O4]
Kiyoshi Fujisawa; Seigo Harakuni; Keigo Ageishi; Edward R. T. Tiekink, 筆頭著者, De Gruyter, Berlin/Boston,NCRS-2023-0333
Zeitschrift für Kristallographie - New Crystal Structures, 2023年10月26日, ［査読有り］

〔主要な業績〕Crystal structure of [N(E),N′(E)]-N,N′-(1,4-phenylenedimethylidyne)bis-3,5-dimethyl-1H-pyrazol-4-amine di-methanol solvate, C18H20N6·2(CH3OH)
Kiyoshi Fujisawa; Keigo Ageishi; Seigo Harakuni; Edward R. T. Tiekink, 筆頭著者, De Gruyter, Berlin/Boston,NCRS-2023-0322
Zeitschrift für Kristallographie - New Crystal Structures, 2023年10月26日, ［査読有り］

〔主要な業績〕New enzyme-model catalysts with high activity and selectivity for oxidative polymerization of 2-phenylphenol
Akiyuki Nakano; Vivek S. Raut; Naoki Asao; Akane Ando; Kiyoshi Fujisawa; Hideyuki Higashimura, 責任著者, Enzyme-inspired copper catalysts having 1,4,7-triazacyclonones substituted at the nitrogen atoms with tBu group(s) have been developed for the regioselective oxidative polymerization of 2-phenylphenol. These in situ prepared catalysts remarkably accelerated the polymerization to produce regioregular poly(2-phenylphenylene oxide). The polymer obtained by using the catalyst with one or two tBu group(s) exhibited a higher number-averaged molecular weight and a narrower molecular distribution than the polymer synthesized by a previous enzyme-model catalyst lacking tBu groups, although a certain amount of free radical coupling occurred in the catalysis with three tBu groups. The enzyme-inspired catalysis would proceed through an end-on peroxide complex different from a side-on peroxide complex formed in the enzyme-model catalysis, achieving both the short reaction time and high molecular weight. Thus, a freestanding film was formed by solvent-casting the present polymer, which was reported to show an ultra-low dielectric constant and high thermal stability, and therefore, it could be promising as an insulating polymer in the upcoming sixth-generation technology., Royal Society of Chemistry (United Kingdom)
Catalysis Science & Technology, 2023年08月30日, ［査読有り］

〔主要な業績〕Coordinatively Unsaturated Nickel Nitroxyl Complex: Structure, Physicochemical Properties, and Reactivity toward Dioxygen
Kiyoshi Fujisawa; Taisei Kataoka; Kohei Terashima; Haruka Kurihara; Felipe de Santis Gonçalves; Nicolai Lehnert, 筆頭著者, MDPI
Molecules, 2023年08月23日, ［査読有り］, ［招待有り］

〔主要な業績〕Superoxide Dismutase‐like Activity of Zeolitic Imidazolate Framework Nanoparticles Comprising Biomimetic Imidazolato‐bridged CuZn Units
Hiroki Nakahara; Akiko Nomura; Shun Tokuda; Mami Okamura; Kiyoshi Fujisawa; Takanori Koitaya; Yasuhiro Yoshida; Shuhei Furukawa; Yutaka Hitomi, Wiley
Chemistry – A European Journal, 2023年07月06日, ［査読有り］

〔主要な業績〕The Copper(II) Coordination Chemistry of Alkyl Substituted Bispyrazole Pyridine Ligands: Structure and Spectral Properties
Kiyoshi Fujisawa * Aoba Yamada; Moeka Koyama; and David James Young, 筆頭著者, Elsevier
Inorganica Chimica Acta, 2023年05月10日, ［査読有り］, ［招待有り］

〔主要な業績〕Structural and Hirshfeld Surface Analysis of Thallium(I) and Indium(III) Complexes of a Soft Scorpionate Ligand
Kiyoshi Fujisawa; Ayaka Kuboniwa; Sang Loon Tan; Edward R. T. Tiekink, 筆頭著者, MDPI
Crystals, 2023年04月29日, ［査読有り］, ［招待有り］

〔主要な業績〕Silver(I) Coordination Polymer Ligated by Bipyrazole Me₄bpzH₂, [Ag(X)(Me₄bpzH₂)] (X = CF₃CO₂⁻ and CF₃SO₃⁻, Me₄bpzH₂ = 3,3′,5,5′-Tetramethyl-4,4′-bipyrazole): Anion Dependent Structures and Photoluminescence Properties
Kiyoshi Fujisawa; Yui Kobayashi; Mitsuki Okano; Ryota Iwabuchi; Shiori Kondo; David James Young, 筆頭著者, MDPI
Molecules, 2023年03月24日, ［査読有り］, ［招待有り］

〔主要な業績〕The crystal structure of nitroxyl-κ N-{hydridotris(3-trifluoromethyl-5-methylpyrazolyl-1-yl-κN 3)borato}nickel(II), C15H13BF9N7NiO
Kiyoshi Fujisawa; Taisei Kataoka; Kohei Terashima; Edward R. T. Tiekink, 筆頭著者, De Gruyter, Berlin/Boston,NCRS-2022-0369
Zeitschrift für Kristallographie - New Crystal Structures, 2022年12月16日, ［査読有り］

〔主要な業績〕Thermally Stable Manganese(III) Peroxido Complexes with Hindered N3 Tripodal Ligands: Structures and their Physicochemical Properties
Kiyoshi Fujisawa; * Syuhei Sakuma; Riko Ikarugi; Anex Jose; Edward I. Solomon*, 筆頭著者, Elsevier
Journal of Inorganic Biochemistry (special Issue on the occasion of 2021 ACS Award for Distinguished Service in the Advancement of Inorganic Chemistry for Professor Kenneth D. Karlin), 2022年06月30日, ［査読有り］, ［招待有り］

〔主要な業績〕Redetermination of the crystal structure of bis{hydridotris(3,5-dimethylpyrazol-1-yl-κN 3)borato}copper(II), C30H44B2CuN12
Kiyoshi Fujisawa; Moemi Okamura; Edward R. T. Tiekink, 筆頭著者, Walter de Gruyter {GmbH}
Zeitschrift für Kristallographie - New Crystal Structures, 2022年02月23日, ［査読有り］

〔主要な業績〕Crystal structure of bis{hydridotris(3-trifluoromethyl-5-methylpyrazolyl-1-yl)borato-κN 3}manganese(II), C30H26B2F18MnN12
Riko Ikarugi; Kiyoshi Fujisawa; Edward R. T. Tiekink, 責任著者, Walter de Gruyter {GmbH}
Zeitschrift für Kristallographie - New Crystal Structures, 2022年02月23日, ［査読有り］

〔主要な業績〕The Influence of Aryl Substituents on the Supramolecular Structures and Photoluminescence of Cyclic Trinuclear Pyrazolato Copper(I) Complexes
Kiyoshi Fujisawa; Mai Saotome; Yoko Ishikawa; David James Young, 筆頭著者, {MDPI} {AG}
Nanomaterials, 2021年11月17日, ［査読有り］, ［招待有り］

〔主要な業績〕Mannich Reaction of α-Aminomaleimides with Imines
Wei Han; Fan Liu; Kiyoshi Fujisawa; Takeshi Oriyama, The Chemical Society of Japan
Chemistry Letters, 2021年06月26日, ［査読有り］

Synthesis and Structural Characterization of a Silver(I) Pyrazolato Coordination Polymer
Kiyoshi Fujisawa; Takuya Nemoto; Yui Morishima; Daniel B. Leznoff, 筆頭著者, MDPI
Molecules, 2021年02月15日, ［査読有り］, ［招待有り］

Impact of Oxygen-Donor Charge on adjacent Nitrogen-Donor Interactions in Eu³⁺ Complexes of Mixed N,O-Donor Ligands Demonstrated on Ten-Fold [Eu(TPAMEN)]³⁺ chelate complex
Kathleen SCHNAARS; Masashi KANEKO; Kiyoshi FUJISAWA, ラスト(シニア)オーサー, American Chemical Society
Inorganic Chemistry, 2021年01月27日, ［査読有り］

Crystal structure of chlorido{hydridotris[3-phenyl-5-methylpyrazol-1-yl-κN³]borato}copper(II), C₃₀H₂₈BClCuN₆
Kiyoshi Fujisawa; Masaya Shimizu; Edward; R.T. Tiekink, 筆頭著者, De Gruyter, Berlin/Boston
Zeitschrift für Kristallographie - New Crystal Structures, 2021年01月26日, ［査読有り］

Crystal structure of chlorido{hydridotris[3,5-dimethylpyrazol-1-yl-κN³]borato}(3,5-dimethylpyrazol-1-yl-κN)copper(II), C₂₀H₃₀BClCuN₈
Kiyoshi Fujisawa; Edward; R.T. Tiekink, 筆頭著者, De Gruyter, Berlin/Boston
Zeitschrift für Kristallographie - New Crystal Structures, 2021年01月26日, ［査読有り］

Multinuclear magnetic resonance studies of five silver(I) trinuclear pyrazolate complexes
Kiyoshi Fujisawa; Mitsuki Okano; Manuel Martín-Pastor; Rubén López-Sánchez; José Elguero; Ibon Alkorta, 筆頭著者, Springer
Structural Chemistry, 2020年10月13日, ［査読有り］

Crystal structure of {hydridotris[3-(t-butyl)-5-isopropylpyrazol-1-yl-κN3]borato}thallium(I), C₃₀H₅₂BN₆Tl
Kiyoshi Fujisawa; Daichi Shimizu; Edward; R.T. Tiekink, 筆頭著者, De Gruyter, Berlin/Boston
Zeitschrift für Kristallographie - New Crystal Structures, 2020年10月01日, ［査読有り］

Crystal Structure of Carbonyl{hydridotris[3-phenyl-5-methylpyrazol-1-yl]borato-N,N’,N’’}copper(I), C₃₁H₂₈BCuN₆O
Kiyoshi Fujisawa; Makoto Yabe; Edward; R.T. Tiekink, 筆頭著者, AbstractC31H28BCuN6O, monoclinic, P21/n (no. 14), a = 11.506(3) Å, b = 16.122(3) Å, c = 15.805(3) Å, β = 99.433(3)°, V = 2892.2(11) Å3, Z = 4, Rgt(F) = 0.0501, wRref(F2) = 0.1260, T = 193(2) K., De Gruyter, Berlin/Boston
Zeitschrift für Kristallographie - New Crystal Structures, 2020年08月28日, ［査読有り］

Structures and Photoluminescence of Coinage Metal(I) Phenylpyrazolato Trinuclear Complexes [M(3,5-Et2-4-Ph-pz)]3 and Arene Sandwich Complexes {[Ag(3,5-Et2-4-Ph-pz)]3}2(Ar) (Ar = Mesitylene and Toluene)
Kiyoshi Fujisawa, 筆頭著者, The Chemical Society of Japan
Chemistry Letters, 2020年06月05日, ［査読有り］

Synthesis and Characterization of Catecholato Copper(II) Complexes with Sterically Hindered Neutral and Anionic N3 Type Ligands: Tris(3,5-diisopropyl-1-pyrazolyl)methane and Hydrotris(3,5-diisopropyl-1-pyrazolyl)borate
Kiyoshi Fujisawa; Tetsuya Ono; Moemi Okamura, 筆頭著者, {MDPI} {AG}
Inorganics, 2020年05月18日, ［査読有り］, ［招待有り］

Activation of Non-Heme Iron-Nitrosyl Complexes: Turning Up the Heat
Nicolai Lehnert; Kiyoshi Fujisawa; Stephanie Camarena; Hai T. Dong; Corey J. White, 責任著者, American Chemical Society ({ACS})
ACS Catalysis, 2019年11月01日, ［査読有り］, ［招待有り］

Structures and Properties of Dinitrosyl Iron and Cobalt Complexes Ligated by Bis(3,5-diisopropyl-1-pyrazolyl)methane
Haruka Kurihara; Ayuri Ohta; Kiyoshi Fujisawa, 責任著者, MDPI
Inorganics, 2019年09月20日, ［査読有り］, ［招待有り］

Structures and Photoluminescence of Silver(I) and Gold(I) Cyclic Trinuclear Complexes with Aryl Substituted Pyrazolates
Kiyoshi Fujisawa, 責任著者, The Chemical Society of Japan
Chemistry Letters, 2019年06月05日, ［査読有り］

Stable Ferrous Mononitroxyl {FeNO}8 Complex with a Hindered Hydrotris(pyrazolyl)borate Coligand: Structure, Spectroscopic Characterization, and Reactivity Toward NO and O2
Kiyoshi Fujisawa; Shoko Soma; Haruka Kurihara; Ayuri Ohta; Hai T. Dong; Yurika Minakawa; Jiyong Zhao; E. Ercan Alp; Michael Y. Hu; Nicolai Lehnert, 筆頭著者, American Chemical Society
Inorganic Chemistry, 2019年04月01日, ［査読有り］

Binuclear and mononuclear copper(II) chlorido complexes with hindered neutral N3 type ligands: Influence of ligand framework and charge on their structure and physicochemical properties
Kiyoshi Fujisawa, 筆頭著者, Elsevier
Inorganica Chimica Acta (Rabindranath (Rabi) Mukherjee special volume), 2018年10月22日, ［査読有り］, ［招待有り］

Syntheses and Structures of d¹⁰Coinage Metal Complexes of Electron-Accepting Phosphine Ligands Featuring a 3,3,4,4,5,5-Hexafluorocyclopentene Framework
Agou, T.; Wada, N.; Fujisawa, K.; Hosoya, T.; Mizuhata, Y.; Tokitoh, N.; Fukumoto, H.; Kubota, T., American Chemical Society
Inorganic Chemistry, 2018年04月23日, ［査読有り］

A cobalt-nitrosyl complex with a hindered hydrotris(pyrazolyl) borate coligand: detailed electronic structure, and reactivity towards dioxygen
Kiyoshi Fujisawa; Shoko Soma; Haruka Kurihara; Hai T. Dong; Max Bilodeau; Nicolai Lehnert, The cobalt-nitrosyl complex [Co(NO)(L3)] is supported by a highly hindered tridentate nitrogen ligand, hydrotris(3-tertiary butyl-5-isopropyl-1-pyrazolyl) borate (denoted as L3(-)), and shows a linear Co-N-O unit. This complex was prepared by the reaction of the potassium salt of L3(-) with the cobalt-nitrosyl precursor [Co(NO)(2)(tmeda)](BPh4) (tmeda = N, N, N,' N'-tetramethylethylenediamine). The obtained cobalt-nitrosyl complex as well as the corresponding products from the reaction with dioxygen, [Co(eta(2)-O2N) (L3)] and [Co(eta(2)-O2NO)(L3)], were characterised by X-ray crystallography and a number of spectroscopic methods including IR/far-IR, UV-Vis, and NMR spectroscopy. We also performed MCD measurements and DFT calculations to further elucidate the electronic structure of [Co(NO)(L3)] and the optical properties of the complex. The MCD spectra reveal two NO-to-Co charge-transfer transitions with strong excited state displacements that give rise to vibrational progressions in the MCD spectra, indicative of a very covalent Co-NO bond. These results provide new insight into the properties of the Co-NO bond and the electron distribution in the complex, which is best described as [Co-II(NO-)(L3)]., ROYAL SOC CHEMISTRY
DALTON TRANSACTIONS, 2017年10月, ［査読有り］, ［招待有り］

A personal perspective on the discovery of dioxygen adducts of copper and iron by Nobumasa Kitajima
Kiyoshi Fujisawa, Transition metal-dioxygen complexes have fascinated bioinorganic and inorganic chemists for over half a century. The late Nobumasa Kitajima was one of the very successful researchers in this field. Despite his short career (40 years old), he made many important contributions. This Commentary highlights his important accomplishments and how they have impacted subsequent work in this area., SPRINGER
JOURNAL OF BIOLOGICAL INORGANIC CHEMISTRY, 2017年04月, ［査読有り］, ［招待有り］

Comparison of thallium(I) complexes with mesityl-substituted tris(pyrazolyl)hydroborate ligands, [Tl{HB(3-Ms-5-Mepz)(3)}] and [Tl{HB(3-Ms-5-Mepz)(2)(3-Me-5-Mspz)}]
Kiyoshi Fujisawa; Masaya Shimizu; Robert K. Szilagyi, Tris(pyrazolyl) borate (scorpionate) ligands can be considered as the most prolific ligands in contemporary coordination chemistry due to the availability of various steric and electronic substituents at the pyrazolyl rings that allow fine-tuning of the open-coordination site for metal centres. The thallium(I) complexes of anionic tridentate-chelating scorpionate ligands, namely [tris(3-mesityl-5-methyl-1H-pyrazol-1-yl-kappa N-2) hydroborato] thallium(I) monohydrate, [Tl(C39H46BN6)]center dot H2O, (I), and [bis(3-mesityl-5-methyl-1H-pyrazol-1-yl-kappa N-2)(5-mesityl-3-methyl-1H-pyrazol-1-yl-kappa N-2) hydroborato] thallium(I), [Tl(C39H46BN6)], (II), show a {(TlN3)-N-I} coordination, with average Tl-I-N bond lengths of 2.53 and 2.55 angstrom in (I) and (II), respectively. The overall Tl-I coordination geometry is distorted trigonal pyramidal, with the average N-Tl-I-N angle being approximately 73 degrees for both. The dihedral angle between the planes of the pyrazolyl and benzene rings of the mesityl group is 82 degrees in (I), while the corresponding angles in (II) are in the range 64-104 degrees. The structural differences between the two ligands are expected to contribute to the different reactivities of the transition metal coordination complexes towards activation of small molecules such as dioxygen and ethylene., INT UNION CRYSTALLOGRAPHY
ACTA CRYSTALLOGRAPHICA SECTION C-STRUCTURAL CHEMISTRY, 2016年11月, ［査読有り］, ［招待有り］

Mononuclear [tris(2-mercapto-1-tert-butylimidazol-yl-κS²)hydroborato]bismuth(I) Dichlorido Complex: Soft Scorpionate Ligand Can be Coordinated to p-block Elements
Kiyoshi Fujisawa; Ayaka Kuboniwa; Mercedesz Kiss; Robert K. Szilagyi, Tris(pyrazolyl) hydroborate ligands have been utilized in the fields of inorganic and coordination chemistry due to the ease of introduction of steric and electronic substitutions at the pyrazole rings. The development and use of the tris(pyrazolyl) hydroborate ligand, called a 'scorpionate', were pioneered by the late Professor Swiatoslaw Trofimenko. He developed a second generation for his ligand system by the introduction of 3-tert-butyl and 3-phenyl substituents and this new ligand system accounted for many remarkable developments in inorganic and coordination chemistry in stabilizing monomeric species while maintaining an open coordination site. Bismuth is remarkably harmless among the toxic heavy metal p-block elements and is now becoming popular as a replacement for highly toxic metal elements, such as lead. Two bismuth(III) complexes of the anionic sulfur-containing tripod tris(3-tert-butyl-2-sulfanylidene-1H-imidazol-1-yl) hydroborate ligand were prepared. By recrystallization from MeOH/CH2Cl2, orange crystals of dichlorido(methanol-kappa O)[tris(3-tert-butyl-2-sulfanylidene-1H-imidazol-1-yl-kappa S) hydroborato] bismuth(III), [Bi(C21H34BN6S3) Cl-2(CH4O)], (I), were obtained, manifesting a mononuclear structure. By using a noncoordinating solvent, red crystals of the binuclear structure with bridging Cl atoms were obtained, namely di-mu-chlorido-bis{chlorido[tris(3-tert-butyl-2-sulfanylidene-1H-imidazol-1-yl-kappa S) hydroborato] bismuth(III)}, [Bi-2(C21H34BN6S3)(2)Cl-4], (II). These complexes show {(BiS3Cl2O)-S-III} and {(BiS3Cl3)-S-III} coordination geometries with average Bi-III-S bond lengths of 2.73 and 2.78 angstrom in (I) and (II), respectively. The overall Bi-III coordination geometry is distorted octahedral due to stereochemically active lone pairs. The three Bi-III-S bond lengths are almost equal in (I) but show considerable differences in (II), with one long and two shorter distances that also correlate with changes in the UV-Vis and H-1 NMR spectra. For direct measurements of the Bi-S/Cl coordination, ligand K-edge X-ray absorption measurements were carried out in combination with ground and excited-state electronic structure analyses. For p-block elements, these sulfur-containing ligands are useful for preparing the appropriate complexes due to their flexible coordination geometry., International Union of Crystallography
Acta Crystallographica Section C Crystal Structure Communications, 2016年11月, ［査読有り］, ［招待有り］

Scorpionate chemistry at the 50th anniversary
Kiyoshi Fujisawa; Glenn P. A. Yap, INT UNION CRYSTALLOGRAPHY
ACTA CRYSTALLOGRAPHICA SECTION C-STRUCTURAL CHEMISTRY, 2016年11月, ［招待有り］

Distorted tetrahedral nickel-nitrosyl complexes: spectroscopic characterization and electronic structure
Shoko Soma; Casey Van Stappen; Mercedesz Kiss; Robert K. Szilagyi; Nicolai Lehnert; Kiyoshi Fujisawa, The linear nickel-nitrosyl complex [Ni(NO)(L3)] supported by a highly hindered tridentate nitrogen-based ligand, hydrotris(3-tertiary butyl-5-isopropyl-1-pyrazolyl)borate (denoted as L3), was prepared by the reaction of the potassium salt of the ligand with the nickel-nitrosyl precursor [Ni(NO)(Br)(PPh (3) ) (2) ]. The obtained nitrosyl complexes as well as the corresponding chlorido complexes [Ni(NO)(Cl)(PPh (3) ) (2) ] and [Ni(Cl)(L3)] were characterized by X-ray crystallography and different spectroscopic methods including IR/far-IR, UV-Vis, NMR, and multi-edge X-ray absorption spectroscopy at the Ni K-, Ni L-, Cl K-, and P K-edges. For comparative electronic structure analysis we also performed DFT calculations to further elucidate the electronic structure of [Ni(NO)(L3)]. These results provide the nickel oxidation state and the character of the Ni-NO bond. The complex [Ni(NO)(L3)] is best described as [Ni (II) (NO (-) )(L3)], and the spectroscopic results indicate that the phosphane complexes have a similar [Ni (II) (NO (-) )(X)(PPh (3) ) (2) ] ground state., SPRINGER
JOURNAL OF BIOLOGICAL INORGANIC CHEMISTRY, 2016年09月, ［査読有り］, ［招待有り］

Extraction Behavior of Rare-earth Elements Using a Mono-alkylated Diglycolamic Acid Extractant
Kojiro Shimojo; Iori Fujiwara; Kiyoshi Fujisawa; Hiroyuki Okamura; Tsuyoshi Sugita; Tatsuya Oshima; Yoshinari Baba; Hirochika Naganawa, Liquid-liquid extraction of rare-earth (RE) cations has been investigated using N-dodecyldiglycolamic acid (C(12)DGAA) with a secondary amide group, and compared with that using N,N-dioctyldiglycolamic acid (DODGAA) with a tertiary amide group. C(12)DGAA enables quantitative transfer of all RE cations from moderately acidic solution, while being selective toward the heavier RE cations, and performs better than typical carboxylic-acid-type extractants. However, C(12)DGAA provides low extraction performance and separation ability for RE cations compared with DODGAA because of the weaker basicity of the amide oxygen. Slope analysis demonstrated that RE3+ transfer with C(12)DGAA proceeded through a proton-exchange reaction, forming a 1:3 complex, RE(C(12)DGAA)(3). Structural characterization by X-ray diffraction revealed that three N-butyldiglycolamic acid (C(4)DGAA) molecules coordinated to the La3+ central ion in a tridentate fashion and the La3+ primary coordination sphere consisted of three oxygen atoms from the amide group, three oxygen atoms from the ether group, and three oxygen atoms from the carboxy group., JAPAN ASSOC SOLVENT EXTRACTION
SOLVENT EXTRACTION RESEARCH AND DEVELOPMENT-JAPAN, 2016年, ［査読有り］

Structure and photoluminescence of silver(I) trinuclear halopyrazolato complexes
Yui Morishima; David James Young; Kiyoshi Fujisawa, Five halogen substituted pyrazolates, 4-chloro-3,5-diisopropylpyrazole (4-Cl-3,5-iPr(2)pzH), 4-bromo-3,5-diisopropylpyrazole (4-Br-3,5-iPr(2)pzH), 4-iodo-3,5-diisopropylpyrazole (4-I-3,5-iPr(2)pzH), 4-chtoro-3,5-diphenylpyrazole (4-Cl-3,5-Ph(2)pzH), and 4-bromo-3,5-diphenylpyrazole (4-Br-3,5-Ph(2)pzH), were conveniently prepared by halogenation of the appropriate pyrazoles with N-halosuccinimides (NXS) (X = Cl, Br, and I) followed by complexation of the pyrazolate anions with silver(I)) nitrate. Single crystal X-ray analysis revealed either dimeric trinuclear {Ag(mu-4-X-3,5-R(2)pz)](3)}(2) (R = iPr, X = Cl, Br, and I) or trinuclear [Ag(mu-4-X 3,5-R(2)pz)](3) (R = iPr, X = I: R = Ph, X = Cl, R = Ph, X = Br) structures, the latter held together with argentophilic interactions (Ag center dot center dot center dot Ag interactions) that could also be observed in the Raman spectra. The electronegativity of the halogen substituent could be correlated with the strength of the Ag...Ag interaction and the wavelength of solid-state photoluminescence. All complexes were emissive on UV irradiation at low temperatures, with the colour of emission from the diisopropyl substituted analogues red shifted by the halogens in the order Cl (red) > Br (orange) > I (yellow). Emission from the diphenyl substituted analogues was dominated by the extended aromatic system and was largely invariant to the halogens., ROYAL SOC CHEMISTRY
DALTON TRANSACTIONS, 2014年11月, ［査読有り］

Conversion of Carbon Dioxide to Oxalate by α-Keto Copper Complexes
Hideyuki Takisawa; Yui Morishima; Shoko Soma; Robert Szilagyi; Kiyoshi Fujisawa, The alpha-ketocarboxylatocopper(II) complex [{Cu(L1)},{O2CC(O)CH(CH3)(2)}] can be spontaneously converted into the binuclear oxalatocopper(II) complex [{Cu(L1)}(2)(mu-C2O4)] upon exposure to O-2/CO2 gas. C-13-labeling experiments revealed that oxalate ions partially incorporated (CO2)-C-13 molecules. Furthermore, the bicarbonatocopper(I) complex (NEt4) [Cu(L1){O2C-(OH)}] in an Ar atmosphere and the alpha-ketocarboxylatocopper(1) complex Na[Cu(L1){O2CC-(O)CH(CH3)(2)}] in an 02 atmosphere were also transformed spontaneously into the oxalato complex [{Cu(L1)}2(mu-C2O4)]., American Chemical Society
Inorganic Chesmitry, 2014年08月, ［査読有り］

L-edge X-ray absorption spectroscopy and DFT calculations on Cu 2O2 species: Direct electrophilic aromatic attack by side-on peroxo bridged dicopper(II) complexes
Munzarin F. Qayyum; Ritimukta Sarangi; Kiyoshi Fujisawa; T. Daniel P. Stack; Kenneth D. Karlin; Keith O. Hodgson; Britt Hedman; Edward I. Solomon, The hydroxylation of aromatic substrates catalyzed by coupled binuclear copper enzymes has been observed with side-on-peroxo-dicopper(II) (P) and bis-μ-oxo-dicopper(III) (O) model complexes. The substrate-bound-O intermediate in [Cu(II)2(DBED)2(O)2] 2+ (DBED = N,N′-di-tert-butyl-ethylenediamine) was shown to perform aromatic hydroxylation. For the [Cu(II)2(NO 2-XYL)(O2)]2+ complex, only a P species was spectroscopically observed. However, it was not clear whether this O-O bond cleaves to proceed through an O-type structure along the reaction coordinate for hydroxylation of the aromatic xylyl linker. Accurate evaluation of these reaction coordinates requires reasonable quantitative descriptions of the electronic structures of the P and O species. We have performed Cu L-edge XAS on two well-characterized P and O species to experimentally quantify the Cu 3d character in their ground state wave functions. The lower per-hole Cu character (40 ± 6%) corresponding to higher covalency in the O species compared to the P species (52 ± 4%) reflects a stronger bonding interaction of the bis-μ-oxo core with the Cu(III) centers. DFT calculations show that 10-20% Hartree-Fock (HF) mixing for P and ∼38% for O species are required to reproduce the Cu-O bonding
for the P species this HF mixing is also required for an antiferromagnetically coupled description of the two Cu(II) centers. B3LYP (with 20% HF) was, therefore, used to calculate the hydroxylation reaction coordinate of P in [Cu(II)2(NO2-XYL)(O2)] 2+. These experimentally calibrated calculations indicate that the electrophilic attack on the aromatic ring does not involve formation of a Cu(III)2(O2-)2 species. Rather, there is direct electron donation from the aromatic ring into the peroxo σ* orbital of the Cu(II)2(O22-) species, leading to concerted C-O bond formation with O-O bond cleavage. Thus, species P is capable of direct hydroxylation of aromatic substrates without the intermediacy of an O-type species. © 2013 American Chemical Society., American Chemical Society
Journal of the American Chemical Society, 2013年11月20日, ［査読有り］

[Bis(3,5-diisopropylpyrazol-1-yl-κN²)dihydroborato](triphenylphosphine-κP) copper(I)
Kiyoshi Fujisawa; Naoto Noguchi; Yuki Noguchi; Nicolai Lehnert, In the title compound, [Cu(C18H32BN 4)(C18H15P)], the CuI ion is coordinated by two N atoms from the anionic bidentate chelating bis(3,5-diisopropylpyrazol-1-yl)dihydroborate ligand [average Cu - N distance = 1.994 (3) Å] and the P atom from a triphenylphosphane ligand [Cu - P distance = 2.1676 (8) Å] in a trigonal geometry [the sum of the angles around the CuI atom is 359.6 (1)°]. The N - Cu - N angle between adjacent coordinated pyrazole-ring N atoms is 98.99 (9)°, while the average N - Cu - P angle between the coordinated pyrazole N atom and the triphenylphosphane P atom is 130.3 (1)°. © 2013 International Union of Crystallography., International Union of Crystallography
Acta Crystallographica Section C Crystal Structure Communications, 2013年09月, ［査読有り］, ［招待有り］

[Tris(3-adamantyl-5-isopropylpyrazol-1-yl-κN²)hydroborato]thallium(I): The Scorpionate with the most bulk?
Kiyoshi Fujisawa; Hideyuki Takisawa, In the thallium(I) complex, [Tl(C48H70BN6)], of tris[3-(adamantan-1-yl)-5-isopropylpyrazol-1-yl]hydroborate, the most hindered scorpionate ligand, the Tl-I ion is coordinated by three N atoms from the anionic tridentate chelating ligand [average Tl-N bond length = 2.522 (4) angstrom] in a distorted trigonal-pyramidal environment [average N-Tl-N angle around the Tl-I ion = 76.4 (1)degrees]. This coordination geometry is compared with that of the reported Tl-I complex of the super-hindered tris(7-tert-butylindazol-2-yl) hydroborate ligand., International Union of Crystallography
Acta Crystallographica Section C Crystal Structure Communications, 2013年09月, ［査読有り］, ［招待有り］

Supramolecular Isomerism in a Cadmium Bis(N‑Hydroxyethyl,N‑isopropyldithiocarbamate) Compound: Physiochemical Characterization of Ball (n=2) and Chain (n=∞) Forms of {Cd[S₂CN(iPr)CH₂CH₂OH]₂•solvent}_n
Yee Seng Tan; Anna L Sudlow; Kieran C Molloy; Yui Morishima; Kiyoshi Fujisawa; Wendy J. Jackson; Bill Henderson; Siti Nadiah Binti Abdul Halim; Seik Weng Ng; d Edward; R.T. Tiekink, Needles of [{Cd[S2CN(iPr)CH2CH2OH] 2}3·MeCN]∞ (2) were harvested from a dry acetonitrile solution of Cd[S2CN(iPr)CH2CH 2OH]2 after one or two days and proved to be a coordination polymer in which all dithiocarbamate ligands are μ2,κ2-tridentate, bridging two cadmium atoms and simultaneously chelating one of these. If the same solution was allowed to stand for at least several days, 2 is replaced by blocks comprising a supramolecular isomer of 2, dimeric 1, with formula {Cd[S2CN(iPr)CH 2CH2OH]2}2·2H 2O·2MeCN, and two ligands coordinating μ2, κ2 as in 2 and the other two purely κ2- chelating. The time dependency correlates with the pivotal role of water in driving the conversion of "chain" 2 to "ball" 1
crystals of 2 could not be isolated from "wet" acetonitrile. When each of 1 and 2 are dissolved in solution, they exhibit comparable spectroscopic attributes (1H, 13C, and 113Cd NMR and UV/vis), indicating the solution structures are the same. Both 1 and 2 are luminescent in the solid state with 1 being significantly brighter than 2. Greenockite CdS nanoparticles are generated by the thermal decomposition of both 1 and 2. © 2013 American Chemical Society., American Chemical Society
Crystal Growth & Design, 2013年07月03日, ［査読有り］

Development of new polymerization catalysts with manganese(II) complexes
Kiyoshi Fujisawa; Masaaki Nabika, Many transition metal catalysts including both early and late transition metal ions have been investigated for olefin polymerization and copolymerization reactions. Less attention has been paid to group 7 metal catalysts. Yet, manganese(II)-based catalysts are expected to have features distinct from early and late transition metal catalysts. In this context, the present review summarizes our recent results and strategy about ethylene polymerization and ethylene copolymerization with 1-hexene with manganese(II)-based catalysts. © 2012 Elsevier B.V.., Elsevier
Coordination Chemistry Reviews, 2013年01月01日, ［査読有り］, ［招待有り］

Purification and characterization of a highly thermostable, oxygen-resistant, respiratory [NiFe]-hydrogenase from a marine, aerobic hydrogen-oxidizing bacterium Hydrogenovibrio marinus
Ki-Seok Yoon; Keiichi Fukuda; Kiyoshi Fujisawa; Hirofumi Nishihara, The membrane-bound [NiFe]-hydrogenase from Hydrogenooibrio marinus (HmMBH) was purified homogeneously under anaerobic conditions. Its molecular weight was estimated as 110 kDa, consisting of a heterodimeric structure of 66 kDa and 37 kDa subunits. The purified enzyme exhibited high activity in a wide temperature range: 185 U/mg at 30 degrees C and 615 U/mg at 85 degrees C (the optimum temperature). The Km and k(cat)/K(m) values for H(2) were, respectively, 12 mu M and 8.58 x 10(7) M(-1) s(-1). The optimum reaction pH was 7.8, but its stability was particularly high at pH 4.0-7.0. Results show that HmMBH was remarkably thermostable and oxygen-resistant: its half-life was 75 h at 80 degrees C under H(2), and more than 72 h at 4 degrees C under air. The air-oxidized HmMBH for 72 h showed only weak EPR signals of Ni-B, suggesting a structural feature in which the active center is not easily oxidized. Copyright (C) 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved., PERGAMON-ELSEVIER SCIENCE LTD
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY, 2011年06月, ［査読有り］

Pyrazolate-bridged group 11 metal(I) complexes: Substituent effects on the supramolecular structures and physicochemical properties
Kiyoshi Fujisawa; Yoko Ishikawa; Yoshitaro Miyashita; Ken-ichi Okamoto, Polynuclear homoleptic pyrazolate-bridged group 11 metal(I) complexes with three different alkyl substituted pyrazolate anions, 3,5-diisopropylpyrazolate (3,5-iPr(2)pz = L1 ), 3-tert-butyl-5-isopropylpyrazolate (3-tBu-5-iPrpz = L3 ), and 3,5-di-tert-butylpyrazolate (3,5-tBu(2)pz = L4 ), i. e. [Cu(mu-3,5-iPr(2)pz)](3) (CuL1), [Ag(mu-3,5-iPr(2)pz)](3) (AgL1), [Au(mu-3,5-iPr(2)pz)](3) (AuL1), [Cu(mu-3-tBu-5-iPrpz)](4) (CuL3), [Ag(mu-3-tBu-5-iPrpz)](3) (AgL3), [Au(mu-3-tBu-5-iPrpz)](4) (AuL3), [Cu(mu-3,5-tBu(2)pz)](4) (CuL4), [Ag(mu-3,5-tBu(2)pz)](4) (AgL4), and [Cu(mu-3,5-tBu(2)pz)](4) (AuL4), were systematically synthesized in order to investigate the influence of pyrazole bulkiness on their structures and physicochemical properties. The structural characterization indicates that the geometries are greatly influenced by the steric hindrance exerted by the substituent groups of the pyrazolyl rings and the differences of the central metal (I) ionic radius (Cu(+) < Au(+) < Ag(+)). These complexes were also characterized by spectroscopic techniques, namely, UV-Vis, IR/far-IR, Raman, and luminescence spectroscopy. (C) 2010 Elsevier B. V. All rights reserved., ELSEVIER SCIENCE SA
INORGANICA CHIMICA ACTA, 2010年10月, ［査読有り］, ［招待有り］

Oxygen Activation at Mononuclear Nonheme Iron Centers: A Superoxo Perspective
Anusree Mukherjee; Matthew A. Cranswick; Mrinmoy Chakrabarti; Tapan K. Paine; Kiyoshi Fujisawa; Eckard Muenck; Lawrence Que, Dioxygen (O(2)) activation by iron enzymes is responsible for many metabolically important transformations in biology. Often a high-valent iron oxo oxidant is proposed to form upon O(2) activation at a mononuclear nonheme iron center, presumably via intervening iron superoxo and iron peroxo species. While iron(IV) oxo intermediates have been trapped and characterized in enzymes and models, less is known of the putative iron(III) superoxo species. Utilizing a synthetic model for the 2-oxoglutarate-dependent monoiron enzymes, [ (Tp(iPr2))Fe(II)(O(2)CC(O)CH(3))], we have obtained indirect evidence for the formation of the putative iron(III) superoxo species, which can undergo one-electron reduction, hydrogen-atom transfer, or conversion to an iron(IV) oxo species, depending on the reaction conditions. These results demonstrate the various roles that the iron( Ill) superoxo species can play in the course of O(2) activation at a nonheme iron center., AMER CHEMICAL SOC
INORGANIC CHEMISTRY, 2010年04月, ［招待有り］

Influences of Steric Bulkiness in Hydrotris(pyrazolyl)borate Ligands on Ethylene Polymerization Reaction
Masaaki Nabika; Seiki Kiuchi; Tatsuya Miyatake; Kiyoshi Fujisawa, Manganese(II) complex catalysts with hydrotris(pyrazolyl)borate ligands have been examined on their catalytic performance in ethylene polymerization and ethylene/1-hexene copolymerization. The activities of [Mn(L6)(Cl)(NCMe)] (1) and [Mn(L10)(Cl)] (2) activated by Al(i-Bu)(3)/[Ph(3)C][B(C(6)F(5))(4)] for ethylene polymerization go up to 326 and 11 kg mol (cat(-1)) h(-1), respectively, (L6(-) = hydrotris(3-phenyl-5-methyl-1-pyrazolyl)borate anion, L10(-) = hydrotris(3-adamantyl-5-isopropyl-1-pyrazolyl)borate anion). In particular, for ethylene/1-hexene copolymerization, complex 1 gives high-molecular-weight poly(ethylene-co-1-hexene)s with the highest M(w), of 439,000 in manganese olefin polymerization catalyst systems. Moreover, the 1-hexene incorporation by complex 1 seems more efficient than that by [Mn(L3)(Cl)] (4) (L3(-) = hydrotris(3-tertiary butyl-5-isopropyl-1-pyrazolyl)borate anion). In this work, we demonstrated that the coordination geometry and coordination number are also important factors for ethylene polymerization reaction as well as steric hindrances and ligand frameworks in our manganese(II) catalysts. (C) 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5720-5727, 2009, JOHN WILEY & SONS INC
JOURNAL OF POLYMER SCIENCE PART A-POLYMER CHEMISTRY, 2009年11月, ［査読有り］

Paired interacting orbitals (PIO) analysis of electronic structures of copper(I) complexes with hydrotris(pyrazolyl)borate ligands
Akinobu Shiga; Kiyoshi Fujisawa, The influence of the hydrotris(pyrazolyl)borate (tpzb) ligand substituents on the electron delocalization of the copper(I) center with carbon monoxide and triphenylphosphine, i.e. the copper(I) carbonyl complexes, [Cu{HB(3,5-iPr(2)pz)(3)}(CO)] (1), [Cu{HB(3,5-Me(2)pz)(3)}(CO)] (2). [Cu{HB(pz)(3)}(CO)] (3), [Cu{HB(3-CF(3)-5-Mepz)(3)}(CO)] (4), and the copper(I) triphenylphosphine complexes [Cu(HB(3,5-iPr(2)pz)(3)}(PPh(3))] (5), [Cu{HB(3-CF(3)-5-Mepz)(3)}(PPh(3))] (6), are studied by using paired interacting orbitals (PIO) analysis. Carbon monoxide is a weak sigma-donor and strong pi-acceptor ligand. The Cu(I)-CO interaction is entirely dominated by pi back bonding between the two degenerate pi* orbitals of carbon monoxide and two t(2) type d orbitals of copper(I) ion. This interaction is clearly expressed by two PIOs, PIO-2 and PIO-3, and the strength of this pi-acceptability is estimated by the summation of their overlap populations (Sigma OP). On the other hand, triphenylphosphine is a strong sigma-donor ligand. The Cu(I)-P interaction is dominated by donation from the P atom to the copper(I) ion and expressed by PIO-1, and the strength of this donative interaction (sigma-donationability) is estimated by the overlap population of PIO-1. These results are consistent with experimental data of the C O stretching frequencies by IR spectroscopy and of (13)C chemical shifts of (13)C O and the broadness of the (31)P Signals Of PPh(3) by (13)C and (31)P NMR spectroscopy. (C) 2009 Elsevier B.V. All rights reserved., ELSEVIER SCIENCE BV
JOURNAL OF MOLECULAR STRUCTURE-THEOCHEM, 2009年11月, ［査読有り］

Copper Complexes with Neutral N4 Tripodal Ligands: Influence of the Number of Nitrogen Donors on Their Structures, Properties, and Reactivity
Kiyoshi Fujisawa; Shingo Chiba; Yoshitaro Miyashita; Ken-ichi Okamoto, Copper coordination complexes of the neutral tetradentate nitrogen-containing ligands tris(3,5-dimethylpyrazol-1-ylmethyl)amine (LON4) and tris(3,5-diisopropylpyrazol-1-ylmethyl)an-dne (LlN4), namely the copper(II) chlorido complexes [Cu`(L0N4)C121 (1) and [Cu"(LlN4)CI2] (2), the copper(II) nitrato complexes [Cu'1(L0N4)(N03)](N03) (3) and [Cu"(LIN4)(NOA(N03) (4), and the copper(II) sulfato complexes [Cu"(LON4) (SOA (5) and jCu'1(L1N4)(S04)1 (6), and the copper(l) complexes tCu1(L0N4fflPF6) (7) and [Cu'(L0N4)(PPh3)1(C104) (8), have been systematically synthesized in order to investigate the influence of the number of nitrogen donors on their structures, properties, and reactivity. All copper(II) complexes were fully characterized by X-ray crystallography and by IR/far-IR, UV/Vis absorption, and ESR spectroscopy. Although the structure of 7 was not determined by X-ray crystallography, this complex and the structurally characterized copper(l) triphenylphosphane complex 8 were fully characterized by IR/far-IR and NMR spectroscopy. A comparison of the copper(11) complexes with two tris(pyrazol-1-ylmethyl)amine ligands with different bulkiness of the pyrazolyl rings has allowed us to evaluate the second coordination sphere effects of the ligands. Moreover, the structures and physicochemical properties of these complexes are compared with those of related complexes containing the neutral tridentate tris (pyrazolyl)me than e ligand and the neutral bidentate bis(pyrazolyl)methane ligand. Finally, the relative stability of the copper(l) complexes is discussed. The influence of the number of nitrogen donors in copper complexes is observed from these systematic results. (0 Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009), WILEY-V C H VERLAG GMBH
EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, 2009年09月, ［査読有り］

Copper(II) nitrato and chloro complexes with sterically hindered tridentate ligands: Influence of ligand framework and charge on their structure and physicochemical properties
Kiyoshi Fujisawa; Hiroaki Iwamoto; Kengo Tobita; Yoshitaro Miyashita; Ken-ichi Okamoto, Copper(II) coordination complexes of the neutral ligand, tris(3-tert-butyl-5-methyl-1-pyrazolyl) methane (L2'), i.e. the copper(II) nitrato complexes [Cu(L2')(NO(3))][Cu(NO(3))4](1/2) (1) and [Cu(L2')(NO(3))](ClO(4)) (2) and the copper(II) chloro complex [Cu(L2')(Cl)](ClO(4)) (3), and its anionic borate analogue, hydrotris(3-tert- butyl-5-methyl-1-pyrazolyl) borate (L2), i. e. the copper(II) nitrato complex [Cu(L2)(NO(3))] (4) and the copper(II) chloro complex [Cu(L2)(Cl)] (5), were synthesized in order to investigate the influence of ligand framework and charge on their structure and physicochemical properties. While X-ray crystallography did not show any definitive trends in terms of copper(II) atom geometry in four-coordinate copper(II) chloro complexes 3 and 5, different structural trends were observed in five-coordinate copper(II) nitrato complexes 1, 2, and 4. These complexes were also characterized by spectroscopic techniques, namely, UV-Vis, ESR, IR/far-IR, and X-ray absorption spectroscopy. (C) 2009 Elsevier B. V. All rights reserved., ELSEVIER SCIENCE SA
INORGANICA CHIMICA ACTA, 2009年09月, ［査読有り］, ［招待有り］

Copper(I) complexes with fluorinated hydrotris(pyrazolyl)borate: Influence of electronic effects on their structure, physicochemical properties, and reactivity
Kiyoshi Fujisawa; Masahiro Yoshida; Yoshitaro Miyashita; Ken-ichi Okamoto, Copper(I) coordination complexes of the anionic fluorinated ligand, hydrotris(3-trifluoromethyl-5-methyl-1-pyrazolyl) borate (L0f(-)), i.e. the copper(I) carbonyl complex, [Cu(I)(L0f)(CO)] (1), the copper(I) triphenylphosphine complex, [Cu(I)(L0f)(PPh(3))] (2), the copper(I) acetonitrile complex, [Cu(I)(L0f)(NCMe)] (3), and the corresponding copper(I) triphenylphosphine complex with hydrotris(3,5-diisopropyl-1-pyrazolyl)borate anion (L1(-)), i.e. [Cu(I)(L1)(PPh(3))] (4), were synthesized in order to investigate the influence of the electron-withdrawing groups on the pyrazolyl rings. The structures of complexes 1, 2, and 4 were determined by X-ray crystallography. While X-ray crystallography did not show definitive trends in terms of copper(I) atom geometry, the clear influence of the electronic structure of the pyrazolyl rings is observed by spectroscopic techniques, namely, IR and multinuclear NMR spectroscopy. Finally, the relative stability of the copper(I) complexes is discussed. (C) 2009 Elsevier Ltd. All rights reserved., PERGAMON-ELSEVIER SCIENCE LTD
POLYHEDRON, 2009年06月, ［査読有り］

Structure and Chemical Properties of a Copper(II) Hydrazido Complex: [{Cu(HB(3,5-iPr₂pz)₃}(μ-NCOOEt)₂]
Kiyoshi Fujisawa; Masaki Sugiyama; Yoshitaro Miyashita; Ken-ichi Okamoto, 配位可能なサイトを持つヒドラジンとヒドロキソ銅(II)錯体の反応を行い、得られた2核ヒドラジド銅(II)錯体の構造を決定した。性質についても言及した。, ELSEVIER SCIENCE BV
Inorg. Chem. Comm., 2009年03月, ［査読有り］

Purification and biochemical characterization of a membrane-bound [NiFe]-hydrogenase from a hydrogen-oxidizing, lithotrophic bacterium, Hydrogenophaga sp AH-24
Ki-Seok Yoon; Yukiko Sakai; Natsuki Tsukada; Kiyoshi Fujisawa; Hirofumi Nishihara, Membrane-bound [NiFe]-hydrogenase from Hydrogenophaga sp. AH-24 was purified to homogeneity. The molecular weight was estimated as 100 +/- 10 kDa, consisting of two different subunits (62 and 37 kDa). The optimal pH values for H-2 oxidation and evolution were 8.0 and 4.0, respectively, and the activity ratio (H-2 oxidation/H-2 evolution) was 1.61 x 10(2) at pH 7.0. The optimal temperature was 75 degrees C. The enzyme was quite stable under air atmosphere (the half-life of activity was c. 48 h at 4 degrees C), which should be important to function in the aerobic habitat of the strain. The enzyme showed high thermal stability under anaerobic conditions, which retained full activity for over 5 h at 50 degrees C. The activity increased up to 2.5-fold during incubation at 50 degrees C under H-2. Using methylene blue as an electron acceptor, the kinetic constants of the purified membrane-bound homogenase (MBH) were V-max=336 U mg(-1), k(cat)=560 s(-1), and k(cat)/K-m=2.24 x 10(7) M-1 s(-1). The MBH exhibited prominent electron paramagnetic resonance signals originating from [3Fe-4S](+) and [4Fe-4S](+) clusters. On the other hand, signals originating from Ni of the active center were very weak, as observed in other oxygen-stable hydrogenases from aerobic H-2-oxidizing bacteria. This is the first report of catalytic and biochemical characterization of the respiratory MBH from Hydrogenophaga., OXFORD UNIV PRESS
FEMS MICROBIOLOGY LETTERS, 2009年01月, ［査読有り］

Spectroscopic and Electronic Structure Studies of Phenolate Cu(II) Complexes: Phenolate Ring Orientation and Activation Related to Cofactor Biogenesis
Somdatta Ghosh; Jordi Cirera; Michael A. Vance; Tetsuya Ono; Kiyoshi Fujisawa; Edward I. Solomon, A combination of spectroscopies and DFT calculations have been used to define the electronic structures of two crystallographically defined Cull-phenolate complexes. These complexes differ in the orientation of the phenolate ring which results in different bonding interactions of the phenolate donor orbitals with the Cull, which are reflected in the very different spectroscopic properties of the two complexes. These differences in electronic structures lead to significant differences in DFT calculated reactivities with oxygen. These calculations suggest that oxygen activation via a Cu(I) phenoxyl ligand-to-metal charge transfer complex is highly endergonic (> 50 kcal/mol), hence an unlikely pathway. Rather, the two-electron oxidation of the phenolate forming a bridging Cu(II) peroxoquinone complex is more favorable (11.3 kcal/mol). The role of the oxidized metal in mediating this two-electron oxidation of the coordinated phenolate and its relevance to the biogenesis of the covalently bound topa quinone in amine oxidase are discussed., AMER CHEMICAL SOC
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 2008年12月, ［査読有り］

Copper(II) complexes with neutral bis(pyrazolyl)methane ligands: The influence of steric hindrance on their structures and properties
Kiyoshi Fujisawa; Ryosuke Kanda; Yoshitaro Miyashita; Ken-ichi Okamoto, By using the neutral bidentate nitrogen-containing ligands; bis(3,5-dimethyl-1-pyrazolyl)methane (L0"), bis(3,5-diisopropyl-1-pyrazolyl)methane (L1"), bis(3-tertiary-butyl-5-isopropyl-1-pyrazolyl)methane (L3"), and bis(3,5-ditertiary-butyl-1-pyrazolyl)methane (L4"), the copper(II) nitrato complexes [Cu(L0")(2)(NO3)]NO3 (1NO(3)), [Cu(L0")(NO3)(2)] (2), [Cu(L1")(NO3)(2)] (3), [Cu(L3")(NO3)(2)] (4), and [Cu(L4")(NO3)(2)] (5), chloro complexes [Cu(L0")(2)Cl](2)(CuCl4) (6CuCl(4)), [Cu(L0")(2)Cl](2)(Cu2Cl6) (6Cu(2)Cl(6)), [Cu(L1")Cl-2] (7), and [Cu(L3")Cl-2] (8), nitrito complexes [Cu(L0")(ONO)(2)] (9) and [Cu(L1")(ONO)(2)] (10), and the complexes with perchlorate ions [Cu(L0")(2)(CH3OH)](ClO4)(2) (11ClO(4)) and [Cu(L1")(2)(H2O)](ClO4)(2) (12ClO(4)) were systematically synthesized and fully characterized by X-ray crystallography and by IR, far-IR, UV-Vis absorption, and ESR spectroscopy. In comparison with the obtained complexes with four bis(pyrazolyl)methanes having different bulkiness at pyrazolyl rings, the second coordination sphere effects on the ligands are discussed in detail. Moreover, the structures and physicochemical properties of these obtained complexes are compared with those of the related complexes with the neutral tridentate tris(pyrazolyl)methane ligand. (C) 2008 Elsevier Ltd. All rights reserved., PERGAMON-ELSEVIER SCIENCE LTD
POLYHEDRON, 2008年04月, ［査読有り］

Aromatic hydroxylation by molecular oxygen performed by mononuclear benzoato iron(II) complexes and preparation of new iron(III) complex with two minus ligand
Kiyoshi Fujisawa; Naoki Tada; Youichirou Nishida; Yoshitaro Miyashita; Ken-ichi Okamoto, A novel oxygen insertion reaction by molecular oxygen into an aromatic C-H bond in benzoato iron(II) complexes [Fe-II {HB(3-Ph-5-MePZ)(3))(eta(1) -O2CC6H4-p-X)(3-Ph-5-MepzH)] (2a (X = Cl), 2b (X = H), and 2c (X = OMe)) is described. The structures of the hydroxylated complexes [Fe-III {HB(3-OPh-5-Mepz)(3-Ph-5-MepZ)(2))(eta(1)-O2CC6H4-p-X)(3-Ph-5-MepzH)] (3a (X=Cl), 3b (X=H), and 3c (X = OMe)) were determined by X-ray crystallography and other spectroscopic characterizations were performed; one of the phenyl rings in the hydrotris(pyrazolyl)borate ligand was hydroxylated. A new purple colored iron(III) complex [Fe-III {HB(3-OPh-5-Mepz)(3-Ph-5-MePZ)(2)}(3-Ph-5-Mepz)] (4), which was obtained by the reaction of 3a with base, is also characterized. (C) 2008 Elsevier B.V. All rights reserved., ELSEVIER SCIENCE BV
INORGANIC CHEMISTRY COMMUNICATIONS, 2008年04月, ［査読有り］

Structural and spectroscopic comparison of five-coordinate cobalt(II) and nickel(II) thiolato complexes with the related four-coordinate complexes
Kiyoshi Fujisawa; Tomonori Kakizaki; Yoshitaro Miyashita; Ken-ichi Okamoto, Five-coordinate thiolato complexes, [L1M(SMeIm)] (M = Co and Ni) (L1 = hydrotris(3,5-diisopropyl-1-pyrazolyl) borate anion and HSMeIm = 2-mercapto-1-methylimidazole), were synthesized. These complexes were compared with the corresponding Cu(II) and Zn(II) complexes with the same ligands and were also compared with the related four-coordinate complexes [L1M(SC6F5)] (HSC6F5 = pentafluorobenzenthiol). All the complexes were characterized by X-ray crystallography and UV-Vis absorption, IR, H-1 NMR, and other spectroscopic techniques. All five-coordinate thiolato complexes, [L1M(SMeIm)] (M = Co, Ni, and Cu), form a distorted square pyramidal structure with a high spin state, and only [L1Zn(SMeIm)] takes a four-coordinate structure with a distorted tetrahedral configuration. The N21-M-S bond angles of the obtained five-coordinate complexes were proportional to the corresponding d value, which comes from between the equatorial basal plane with N4S ligand donor sets and metal ion. These observations and M-S bond distances affect on UV-Vis and far-IR spectral behavior. (C) 2007 Elsevier B.V. All rights reserved., ELSEVIER SCIENCE SA
INORGANICA CHIMICA ACTA, 2008年03月, ［査読有り］, ［招待有り］

Mononuclear and binuclear copper( I)-diazene complexes: A new chapter of copper coordination chemistry
Florian Paulat; Nicolai Lehnert; Yoko Ishikawa; Ken-Ichi Okamoto; Kiyoshi Fujisawa, Starting from copper( II) hydrotris( pyrazolyl) borate precursors and substituted hydrazines, we were able to synthesize mononuclear and binuclear copper( I) - diazene complexes for the first time. The mechanism of these reactions corresponds to a simple hydrazine oxidation by the copper( II) centers. Binuclear diazene complexes contain the central Cu( I) - NR=NR - Cu( I) unit, which we have structurally and spectroscopically characterized. Interestingly, usage of a sterically demanding hydrotris( pyrazolyl) borate ligand that prevents the dimer formation, leads to decomposition of the diazene complex and the isolation of a copper( I) - hydrazine complex. The same is observed when a tris( pyrazolyl) methane ligand is applied. Finally, using 1,1-diphenylhydrazine or the corresponding monophenyl derivative, we were able to obtain mononuclear Cu( I) - diazene complexes. In this case, the phenyl substituent( s) prevent the dimerization, but also stabilize the diazene ligand. Mononuclear and binuclear Cu( I) - diazene complexes are characterized by their intense reddish to purple color, which is caused by an intense Cu-d to diazene-pi* transition in the visible region. Resonance Raman spectra of the diazene complexes show the Cu -N and N - N stretching vibrations in the 500 cm (-1) and 1350 - 1400 cm(-1) energy regions, respectively, in agreement with the diazene description of the complexes. The copper( I) - diazene bond in these complexes is dominated by p backbonding. (c) 2007 Elsevier B. V. All rights reserved., ELSEVIER SCIENCE SA
INORGANICA CHIMICA ACTA, 2008年03月, ［査読有り］, ［招待有り］

Structural and spectroscopic characterization of mononuclear copper(I) nitrosyl complexes: End-on versus side-on coordination of NO to copper(I)
Kiyoshi Fujisawa; Akira Tateda; Yoshitaro Miyashita; Ken-ichi Okamoto; Florian Paulat; V. K. K. Praneeth; Anna Merkle; Nicolai Lehnert, Two crystal structures of the mononuclear copper(I)-nitrosyl complexes [Cu(L3)(NO)] (1) and [Cu(L3')(NO)1(CIO4) (2) with the related coligands L3(-) (hydrotris(3-tert-butyl-5-isopropyl-1-pyrazolyl)borate) and L3' (tris(3-tert-butyl-5-isopropyl-1-pyrazolyl) methane) are presented. These compounds are then investigated in detail using a variety of spectroscopic methods. Vibrational spectra show nu(N-O) at 1698 cm(-1) and nu(Cu-NO) split at 365/338 cm(-1) for 1, which translates to force constants of 12.53 (N-O) and 1.31 mdyn/angstrom (Cu-NO), respectively. The weak Cu-NO force constant is in agreement with the observed instability of the Cu-NO bond. Interestingly, complex 2 with the neutral coligand LT shows a stronger N-O bond, evident from v(N-O) at 1742 cm-1. This difference is attributed to a true second coordination sphere effect, where the covalency of the Cu(I)-NO bond is not altered. The EPR spectrum of 1 is in agreement with the Cu(l)-NO(radical) electronic structure of the complexes, as obtained from density functional theory (DFT) calculations. In addition, an interesting trend between g(II)(g(z)) and the Cu-N-O angle is established. Finally, high-quality MCD spectra of 1 are presented and assigned using TD-DFT calculations. Based on the in-depth spectroscopic characterization of end-on bound NO to copper(l) presented in this work, it is possible to determine the binding mode of the Cu-NO intermediate of Cu nitrite reductase studied by Scholes and co-workers (Usov, O. M.; Sun, Y.; Grigoryants, V. M.; Shapleigh, J. P.; Scholes, C. P., J. Am. Chem. Soc. 2006, 128, 13102-13111) in solution as strongly bent (similar to 135 degrees) but likely not side-on., AMER CHEMICAL SOC
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 2008年01月

X-ray Absorption Spectroscopic and Theoretical Studies on (L)₂[Cu₂S_n]²⁺ Complexes: Disulfide Versus Disulfide(•1-) Bonding
Ritimukta Sarangi; John T. York; Matthew E. Helton; Kiyoshi Fujisawa; Kenneth D. Karlin; William B. Tolman; Keith O. Hodgson; Britt Hedman; Edward I. Solomon, (L)2[Cu2Sn]2+型錯体のX線吸収スペクトル測定とDFT計算による理論的考察を行った。ジスルフィドマイナス２価イオンとジスルフィドアニオンラジカルとの電子状態の違いについて精査した。, AMER CHEMICAL SOC
J. Am. Chem. Soc., 2008年01月, ［査読有り］

Mononuclear and binuclear copper(I) complexes ligated by B is(3 5-diisopropyl-1-pyrazolyl)methane: Insight into the fundamental coordination chemistry of three-coordinate copper(I) complexes with a neutral coligand
Kiyoshi Fujisawa; Yuki Noguchi; Yoshitaro Miyashita; Ken-ichi Okamoto; Nicolai Lehnert, By using the neutral bidentate nitrogen-containing ligand, bis(3,5-diisopropyl-1-pyrazolyl)methane (L1"), the copper(I) complexes [CuL1")(2)](CuCl2)(1CUCl(2)), [Cu(L1")(2)](ClO4) (1ClO(4)), [Cu(L1")](2)(ClO4)(2) (2ClO(4)), [Cu(L1")](2)(BF4)(2) (2BF(4)), [Cu(L1")(NCMe)](PF6) (3PF(6)), [Cu(L1")(PPh3)1(ClO4) (4ClO(4)), [Cu(L1")(PPh3)](PF6) (4PF(6)), [{Cu(L1")(CO)](2)(mu-ClO4)](ClO4) (5ClO(4)), and the copper(II) complexes [{Cu(L1")}(2)(mu-OH)(2)(mu-ClO4)(2)] (6), and [Cu(L1")Cl-2] (7) were systematically synthesized and fully characterized by X-ray crystallography and by IR and H-1 NMR spectroscopy. In the case of copper(II), ESR spectroscopy was also applied. In comparison with the related neutral tridentate ligand L1', bis-chelated copper(I) complexes and binuclear linear-coordinated copper(I) complexes are easy to obtain with L1", like 1CuCl(2), 1ClO(4), 2ClO(4), and 2BF(4). Importantly, stronger and bulkier ligands such as acetonitrile (3PF(6)) and especially triphenylphosphine (4ClO(4) and 4PF(6)) generate three-coordinate structures with a trigonal-planar geometry. Surprisingly, for the smaller ligand carbon monoxide, a mononuclear three-coordinate structure is very unstable, leading to the formation of a binuclear complex (5ClO(4)) with one bridging perchlorate anion, such that the copper(I) centers are four-coordinate. The same tendency is observed for the copper(II) bis(mu-hydroxo) compounds 6, which is additionally bridged by two perchlorate anions. Both copper(II) complexes 6 and 7 were obtained by molecular O-2 oxidation of the corresponding copper(I) complexes. A comparison of the new copper(I) triphenylphosphine complexes 4ClO(4) and 4PF6 with corresponding species obtained with the related tridentate ligands L1' and L1 (8ClO(4) and 9, respectively) reveals surprisingly small differences in their spectroscopic properties. Density functional theory (DFT) calculations are used to shed light on the differences in bonding in these compounds and the spectral assignments. Finally, the reactivity of the different bis(pyrazolyl) methane complexes obtained here toward PPh3, CO, and O-2 is discussed., AMER CHEMICAL SOC
INORGANIC CHEMISTRY, 2007年12月, ［査読有り］

X-ray absorption spectroscopic studies of high-spin Nonheme (Alkylperoxo)iron(III) intermediates
Xiaopeng Shan; Jan-Uwe Rohde; Kevin D. Koehntop; Yuming Zhou; Michael R. Bukowski; Miquel Costas; Kiyoshi Fujisawa; Lawrence Que, The reactions of iron(II) complexes [Fe(Tp(t-Bu,i-Pr))(OH)] (1a, Tp(t-Buj-Pr) = hydrotris(3-tert-butyl-5-isopropyl-1-pyrazolyl)borate), [Fe(6-Me2BPMCN)(OTf)(2)] (1b, 6-Me2BPMCN = N,N'-bis((2-methylpyridin-6-yl)methyl)-N,N'-dimethyl-trans-1,2-diaminocyclohexane), and [Fe((LPy2)-Py-8)(OTf)](OTf) (1c, (LPy2)-Py-8 = 1,5-bis(pyridin-2-ylmethyl)-1,5-diazacyclooctane) with tert-BuOOH give rise to high-spin Fe-III-OOR complexes. X-ray absorption spectra (XAS) of these high-spin species show characteristic features, distinct from those of low-spin Fe-OOR complexes (Rohde, J.-U.; et al. J. Am. Chem. Soc. 2004, 126, 16750-16761). These include (1) an intense 1s -> 3d preedge feature, with an area around 20 units, (2) an edge energy, ranging from 7122 to 7126 eV, that is affected by the coordination environment, and (3) a 1.86-1.96 angstrom Fe-OOR bond, compared to the 1.78 angstrom Fe-OOR bond in low-spin complexes. These unique features likely arise from a flexible first coordination sphere in those complexes. The difference in Fe-OOR bond length may rationalize differences in reactivity between low-spin and high-spin Fe-III-OOR species., AMER CHEMICAL SOC
INORGANIC CHEMISTRY, 2007年10月, ［査読有り］

Synthesis and spectroscopic characterization of copper(II)-nitrito complexes with hydrotris(pyrazolyl)borate and related coligands
Nicolai Lehnert; Ursula Cornelissen; Frank Neese; Tetsuya Ono; Yuki Noguchi; Ken-ichi Okamoto; Kiyoshi Fujisawa, This study focuses on the geometric (molecular) structures, spectroscopic properties, and electronic structures of copper(II)-nitrito complexes as a function of second coordination sphere effects using a set of closely related coligands. With anionic hydrotris(pyrazolyl)borate ligands, one nitrite is bound to copper(II). Depending on the steric demand of the coligand, the coordination mode is either symmetric or asymmetric bidentate, which leads to different ground states of the resulting complexes as evident from EPR spectroscopy. The vibrational spectra of these compounds are assigned using isotope substitution and DFT calculations. The results demonstrate that nu(sym)(N-O) occurs at higher energy than nu(asym)(N-O), which is different from the literature assignments for related compounds. UV-vis absorption and MCD spectra are presented and analyzed with the help of TD-DFT calculations. The principal binding modes of nitrite to Cu(II) and Cu(I) are also investigated applying DFT. Using a neutral tris(pyrazolyl)methane ligand, two nitrite ligands are bound to copper. In this case, a very unusual binding mode is observed where one nitrite is eta(1)-O and the other one is eta(1)-N bound. This allows to study the properties of coordinated nitrite as a function of binding mode in one complex. The N-coordination mode is easily identified from vibrational spectroscopy, where N-bound nitrite shows a large shift of nu(asym)(N-O) to > 1400 cm(-1), which is a unique spectroscopic feature. The optical spectra of this compound exhibit an intense band around 300 nm, which might be attributable to a nitrite to Cu(II) CT transition. Finally, using a bidentate neutral bis(pyrazolyl)methane ligand, two eta(1)-O coordinated nitrite ligands are observed. The vibrational and optical (UV-vis and MCD) spectra of this compound are presented and analyzed., AMER CHEMICAL SOC
INORGANIC CHEMISTRY, 2007年05月, ［査読有り］

Manganese(II) halogeno complexes with neutral tris(3,5-diisopropyl-1-pyrazolyl)methane ligand: Synthesis and ethylene polymerization
Masaaki Nabika; Seiki Kiuchi; Tatsuya Miyatake; Ken-Ichi Okamoto; Kiyoshi Fujisawa, Manganese(II) halogeno complexes containing a neutral tris(3,5-diisopropyl-l-pyrazolyl)methane (referred to as Ll') ligand have been examined on their catalytic performance in ethylene polymerization and ethylene/l-hexene copolymerization. The activities of [Mn(Cl-2)(Ll')] (a) and [Mn(Br)(Ll')](Br) (b) activated by Al(i-Bu)(3)/(Ph3C)[B(C6F5)4] for ethylene polymerization go up to 1600 and 840 kg mol(cat)(-1) h(-1) with a bimodal molecular weight distribution (MwMn) of 4.1 and 4.2, respectively. These results are different from the corresponding manganese(II) complexes with hydrotris(pyrazolyl)borate anion. (c) 2007 Elsevier B.V. All rights reserved., ELSEVIER SCIENCE BV
JOURNAL OF MOLECULAR CATALYSIS A-CHEMICAL, 2007年05月, ［査読有り］

Bond length contraction in zinc-triad complexes ligated by hydrotris(pyrazolyl)borate: [M(Cl){HB(3,5-(i)Pr(2)pz)(3)}] (M = Zn-II, Cd-II, and Hg-II)
Kiyoshi Fujisawa; Yuki Matsunaga; Naoko Ibi; Nagina Amir; Yoshitaro Miyashita; Ken-ichi Okamoto, Bond length contraction in zinc-triad chloro complexes, which were characterized by X-ray crystallography and metal-halogen stretching frequency, is reported., CHEMICAL SOC JAPAN
BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN, 2006年12月, ［査読有り］

Synthesis and physicochemical characterization of zinc(II) and cadmium(II) complexes with simple ligands
Yuki Matsunaga; Kiyoshi Fujisawa; Nagina Amir; Yoshitaro Miyashita; Ken-ichi Okamoto, In order to study the physicochemical properties of Zn-II and Cd-II complexes, complexes with "simple'' supporting ligands were synthesized. Various coordination types were obtained, such as ZnN2S2 in [Zn(SCH2CF3)(2)(L)] (L = sp, (-)-sparteine or hp, homopiperazine), ZnN2O2 in [Zn(OCH(CF3)(2))(2)(sp)], ZnO2S2 in (Et4N)(2) [Zn(OCH2(CF2)(3)CH2O)(SCH2CF3)(2)], ZnN3S in [Zn(SR)(tacn (iPr))](ClO4) (tacn (iPr) = 1,4,7-triisopropyl-1,4,7-triazacyclononane; SR = 1-adamantanethiolate, SC10H15, 1-cyclohexanethiolate, SC6H11, or SCH2CF3), CdN3S in [Cd(SC10H15)(tacn (iPr))](ClO4) and [Cd-3(SCH2CF3)(6)(tacn (iPr))(2)]. The far-i.r., Raman and u.v.-vis. absorption spectra of the complexes are discussed, and the crystal structures of two of the complexes were determined., SPRINGER
TRANSITION METAL CHEMISTRY, 2006年10月, ［査読有り］

Preparation of zinc(II) and cadmium(II) complexes with (-)-sparteine
Yuki Matsunaga; Kiyoshi Fujisawa; Nagina Amir; Yoshitaro Miyashita; Ken-ichi Okamoto, A systematic study on the effects of different metals and halogenide ions was carried out by using [MX2(sp)] (M = Zn and Cd; X = Cl, Br, and I; sp = (-)-sparteine). The complexes have been characterized by X-ray crystallography, and far-IR and Raman spectroscopy., CHEMICAL SOC JAPAN
BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN, 2006年08月, ［査読有り］

Oxygen atom transfer catalytic property of oxorhenium(V) complex with 2-methylquinolin-8-ylamide and tetrachlorocatecholate
Tetuya Ohashi; Yoshitaro Miyashita; Kiyoshi Fujisawa; Ken-ichi Okamoto, New oxorhenium(V) complex was prepared and characterized by an X-ray crystal analysis. The complex showed characteristic releasing property of monodentate ligand and high oxygen atom transfer catalytic activity from 2,6-lutidine-N-oxide to PPh3., CHEMICAL SOC JAPAN
CHEMISTRY LETTERS, 2006年06月, ［査読有り］

X-ray absorption edge spectroscopy and computational studies on LCuO2 species: Superoxide-Cu-II versus peroxide-Cu-III bonding
R Sarangi; N Aboelella; K Fujisawa; WB Tolman; B Hedman; KO Hodgson; EI Solomon, The geometric and electronic structures of two mononuclear CuO2 complexes, [Cu(O-2){HB(3-Ad-5-(i)Prpz)(3)}] (1) and [Cu(O-2)(beta-diketiminate)] (2), have been evaluated using Cu K- and L-edge X-ray absorption spectroscopy (XAS) studies in combination with valence bond configuration interaction (VBCI) simulations and spin-unrestricted broken symmetry density functional theory (DFT) calculations. Cu K- and L-edge XAS data indicate the Cu(II) and Cu(III) nature of 1 and 2, respectively. The total integrated intensity under the L-edges shows that the Psi(*)(LUMO)'s in 1 and 2 contain 20% and 28% Cu character, respectively, indicative of very covalent ground states in both complexes, although more so in 1. Two-state VBCI simulations also indicate that the ground state in 2 has more Cu (vertical bar 3d(8)>) character. DFT calculations show that the Psi(*)(LUMO)'s in both complexes is dominated by O-2(n-) character, although the O-2(n-) character is higher in 1. It is shown that the ligand L plays an important role in modulating Cu-O-2 bonding in these LCuO2 systems and tunes the ground states of 1 and 2 to have dominant Cu(II)-superoxide- like and Cu(III)-peroxide-like character, respectively. The contributions of ligand field (LF) and the charge on the absorbing atom in the molecule (Q(mol)(M)) to L- and K-edge energy shifts are evaluated using DFT and time-dependent DFT calculations. It is found that LF makes a dominant contribution to the edge energy shift, while the effect of Q(mol)(M) is minor. The charge on the Cu in the Cu(III) complex is found to be similar to that in Cu(II) complexes, which indicates a much stronger interaction with the ligand, leading to extensive charge transfer., AMER CHEMICAL SOC
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 2006年06月, ［査読有り］

Synthesis of novel S-bridged heterotrinuclear complexes containing six-membered chelate rings: Structural, spectroscopic, and electrochemical properties of [Co{Rh(apt)(3)}(2)](3+) (apt=3-aminopropanethiolate)
N Amir; M Motonishi; M Fujita; Y Miyashita; K Fujisawa; KI Okamoto, A bidentate ligand, 3-ammopropanethiolate (apt), was synthesized and treated with RhCl3-3H(2)O in basic water to yield a novel mononuclear complex, fac(S)-[Rh(apt)(3)] (1), which was characterized by spectroscopic methods. Furthermore, the reaction of 1 with COCl2-6HO in water formed the linear-type, S-bridged trinuclear complexes Delta Lambda-{Co(Rh(apt)(3)}(2)](3+) (2a) and Delta Delta/Lambda Lambda-[Co(Rh(apt)(3))(2)](3+) (2b), which were characterized by stereochemical, spectrochemical, and electrochemical methods. 2a and 2b are stable and exhibit trivalency in water. X-ray crystallographic analysis of 2a and 2b showed that all of the bridging sulfur atoms are fixed in the R configuration for the A unit and in the S configuration for the A unit, and each complex has six six-membered chelate rings, all of which are in the chair conformation. The crystal structure of the corresponding 2-aminoethanethiolate (act) trinuclear complex Delta Lambda-[Co[Rh(aet)(3))(2)](3+), (4a) was also deter-mined. The structures of 2a and 2b have some differences from that of 4a as a result of the six-membered chelate rings. The Co center dot center dot center dot Rh distances in 2a and 2b [3.0490(4) and 3.063(1) angstrom] are significantly longer than this distance in the aet complex 4a [2.9139(2) angstrom]. The UV/Vis absorption spectra of 2a and 2b indicate a shift to higher energies as compared with 4a and AA/AA-[Co{Rh(aet)(3)}(2)](3+) (4b). The chemical shifts for the NCH2 and SCH2 carbon atoms in 2a and 2b are shifted to higher fields than those for 4a and 4b in the NMR spectra. The Co-III/II redox potential values are -0.56V (2a) and -0.57V (2b) compared with -0.35V (4a) and -0.36V (4b). This shows that the Co-III state is more stable in 2a and 2b than it is in 4a and 4b. (c) Wiley-VCH Verlag GmbH & Co., WILEY-V C H VERLAG GMBH
EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, 2006年03月, ［査読有り］

Structural and electronic differences of copper(I) complexes with tris(pyrazolyl)methane and hydrotris(pyrazolyl)borate ligands
K Fujisawa; T Ono; Y Ishikawa; N Amir; Y Miyashita; K Okamoto; N Lehnert, Copper(I) complexes with tripodal nitrogen-containing neutral ligands such as tris(3,5-diisopropyl-1-pyrazolyl)methane (L1') and tris(3-tertiary-butyl-5-isopropyl-1-pyrazolyl)methane (L3'), and with corresponding anionic ligands such as hydrotris(3,5-diisopropyl-l-pyrazolyl)borate (L1(-)) and hydrotris(3-tertiary-butyl-5-isopropyl-1-pyrazolyl)borate (L3(-)) were synthesized and structurally characterized. Copper(I) complexes [Cu(L1')Cl] (1), [Cu(L1')(OClO3)] (2), [Cu(L1')(NCMe)](PF6) (3a), [Cu(L1')(NCMe)](ClO4) (3b), [Cu(L1')(CO)](PF6) (4a), and [Cu(L1')(CO)](ClO4) (4b) were prepared using the ligand L1'. Copper(I) complexes [Cu(L3')Cl] (5) and [Cu(L3')(NCMe)](PF6) (6) with the ligand L3' were also synthesized. Copper(I) complexes [Cu(L1)(NCMe)] (7) and [Cu(L1)(CO)] (8) were prepared using the anionic ligand L1(-). Finally, copper(I) complexes with anionic ligand L3- and acetonitrile (9) and carbon monoxide (10) were synthesized. The complexes obtained were fully characterized by IR, far-IR, H-1 NMR, and C-13 NMR spectroscopy. The structures of both ligands, L1' and L3', and of complexes 1, 2, 3a, 3b, 4a, 4b, 5, 6, 7, and 10 were determined by X-ray crystallography. The effects of the differences in (a) the fourth ligand and the counteranion, (b) the steric hindrance at the third position of the pyrazolyl rings, and most importantly, (c) the charge of the N3 type ligands, on the structures, spectroscopic properties, and reactivities of the copper(I) complexes are discussed. The observed differences in the reactivities toward O-2 of the copper(I) acetonitrile complexes are traced back to differences in the oxidation potentials determined by cyclic voltammetry. A special focus is set on the carbonyl complexes, where the C-13 NMR and vibrational data are presented. Density functional theory (DFT) calculations are used to shed light on the differences in CO bonding in the compounds with neutral and anionic N3 ligands. In correlation with the vibrational and electrochemical data of these complexes, it is demonstrated that the C-O stretching vibration is a sensitive probe for the "electron richness" of copper(I) in these compounds., AMER CHEMICAL SOC
INORGANIC CHEMISTRY, 2006年02月, ［査読有り］

Sulfur K-edge extended X-ray absorption fine structure spectroscopy of homoleptic thiolato complexes with Zn(II) and Cd(II)
Y Matsunaga; K Fujisawa; N Ibi; M Fujita; T Ohashi; N Amir; Y Miyashita; K Aika; Y Izumi; K Okamoto, The sulfur K-edge extended X-ray absorption fine structure (EXAFS) spectroscopy is applied to homoleptic thiolato complexes with Zn(II) and Cd(II), (Et4N)[Zn(SAd)(3)] (1), (Et4N)(2)[ (Zn(ScHex)(2))(2)(mu-ScHex)(2)] (2), (Et4N)(2)[{Cd(ScHex)(2)}(2)(mu-ScHex)(2)] (3), (Et4N)(2)[{Cd(ScHex)}(4)(mu-ScHex)(6)] (4), [Zn(mu-SAd)(2)](n) (5), and [Cd(mu-SAd)(2)](n) (6) (HSAd = 1-adamantanethiol, HScHex = cyclohexanethiol). The EXAFS results are consistent with the X-ray crystal data of 1-4. The structures of 5 and 6, which have not been determined by X-ray crystallography, are proposed to be polynuclear structures on the basis of the sulfur K-edge EXAFS, far-IR spectra, and elemental analysis. Clear evidences of the S center dot center dot center dot S interactions (between bridging atoms or neighboring sulfur atoms) and the S center dot center dot center dot C-far interactions (in which C-far atom is next to carbon atom directly bonded to sulfur atom) were observed in the EXAFS data for all complexes and thus lead to the reliable determination of the structures of 5 and 6 in combination with conventional zinc K-edge EXAFS analysis for 5. This new methodology, sulfur K-edge EXAFS, could be applied for the structural determination of in vivo metalloproteins as well as inorganic compounds. (C) 2005 Elsevier Inc. All rights reserved., ELSEVIER SCIENCE INC
JOURNAL OF INORGANIC BIOCHEMISTRY, 2006年02月, ［査読有り］, ［招待有り］

Nickel(II) complexes with Schiff bases derived from salicylaldehyde or pentanedione and 3-aminopropanethiol
Amir, N.; Miyashita, Y.; Fujisawa, K.; Okamoto, K.-I., シッフ塩基タイプの配位子を用いて硫黄架橋の2核Ni(II)錯体を合成し、その構造を決定するとともに、性質を明らかにした。
Journal of Coordination Chemistry, 2006年, ［査読有り］

Dichlorooxo(quinoline-8-thiolato-κ²N,S)(triphenylphosphine oxide-κO)rhenium(V) acetone Solvate
Yoshitaro Miyashita; Tetuya Ohashi; Akiomi Imai; Nagina Amir; Kiyoshi Fujisawa; Ken-ichi Okamoto, 表題の錯体の構造をX線解析により決定し、関連錯体との比較を行った。, BLACKWELL PUBLISHING
Acta Crystallogr. Sect. C, 2005年11月, ［査読有り］

Stereoselective formation and properties of mononuclear and polynuclear nickel(II) complexes with 1-amino-2-propanethiolate
M Fujita; Y Miyashita; N Amir; Y Kawamoto; K Kanamori; K Fujisawa; K Okamoto, A mononuclear complex acting as a novel chiral ligand, [Ni(1-Meaet)(2)] (1-Meaet = 1-amino-2-propanethiolate; 1b) was synthesized. Using this mononuclear complex, the S-bridged trinuclear complex [Ni{Ni(1-Meaet)(2)}(2)](2+) (2b), hexanuclear complex [Pd-2{Ni0.6Pd0.4(1-Meaet)(2)}(4)](4+) (3b), and dinuclear complexes [Pt(bpy){Ni(1-Meaet)(2)(H2O)(2)}](2+) (bpy = 2,2'-bypyridine; 4b) and [Pt(bpy) {Ni(1-Meaet)(bpy)}](2+) (5b) were synthesized. Molecular structures for 3b and 5b were determined by X-ray diffraction. In the crystal structure of 3b, two Pd(II) ions are bridged by four metalloligands, cis(S)-[Ni(1-Meaet)(2)] and/or cis(S)-[Pd(1-Meaet)(2)] units, forming a C-4h symmetrical S-bridged hexanuclear structure with high optical selectivity of the ligand, in which all [M(1-MeaCt)(2)] units have the absolute cis(S)-R,S configuration. In the crystal structure of 5b, the Ni(II) ions are surrounded by two 1-Meaet and one bpy to have an approximately octahedral geometry with 50% ligand diastereoselectivity of the mixed crystals Of Delta(RR)/Delta(ss) and Delta(RS)/Delta(RS) configuration. Moreover, the lowering of the nucleophilicity of the sulfur atom was observed by the introduction of the methyl group. The properties of 1b-5b were discussed in comparison with the corresponding act (2-aminoethanethiolate) complexes 1a-5a using X-ray absorption, UV/Vis, IR, far-IR, Raman and NMR spectra, as well as structural analysis. (c) 2005 Elsevier Ltd. All rights reserved., PERGAMON-ELSEVIER SCIENCE LTD
POLYHEDRON, 2005年10月, ［査読有り］

Selective formation of lanthanide(III) complexes with polyaminopolycarboxylate: Unprecedented tetranuclear neodymium(III) complex containing alkoxo and carboxylato bridges
Y Miyashita; M Sanada; MM Islam; N Amir; T Koyano; H Ikeda; K Fujisawa; K Okamoto, Crystal structures of the novel polynuclear Nd(III) complexes, Na-4[{Nd(H2O)}(2)(mu(2)-dptaO)(2)] (1) and K-8[Nd-2{Nd(H2O)(2)}(2)- (mu(2)-dptaO)(2)(mu(3)-dptaO)(2)] (2)(H(4)dptaOH = 2-hydroxypropane-1,3-diamine-N,N,N ',N '-tetraacetic acid), which were selectively formed depending on the difference of counter cations, were determined. These complexes showed weak antiferromagnetic behavior. (c) 2005 Elsevier B.V. All rights reserved., ELSEVIER SCIENCE BV
INORGANIC CHEMISTRY COMMUNICATIONS, 2005年09月, ［査読有り］

Syntheses, structures, and properties of oxorhenium(V) complexes with 2-, 5, and/or 7-substituted 8-quinolinolato ligands
Y Miyashita; T Ohashi; A Imai; N Amir; K Fujisawa; K Okamoto, Five mononuclear oxorhenium(V) complexes containing 8-quinolinolato derivatives, [ReOCl2(2-X-5-Y-7-Z-8-Oqn)(PPh3)] (qn= quinoline; PPh3 = triphenylphosphine; X = Me, Y = Z = H, 1; X = Z = H, Y = Cl, 2; X = H, Y = Z = Cl, 3; X = H, Y = Cl, Z = 1, 4; X = H, Y = Z = Br, 5), were newly synthesized by the reaction of [ReOCl3(PPh3)(2)] with the corresponding 8-hydroxyquinoline ligands. From X-ray crystal structural analyses, all the obtained complexes have the same geometry; the Re=O bond occupies the trans position to the 0 atom of the deprotonated 8-hydroxyquinoline ligand. The complexes, which retain their structures in solution, were characterized on the basis of IR, UV-ViS, P-31 NMR spectra, and cyclic voltammetry. Depending on the existence of 2-Me substituent in the ligands, some stereochemical and electrochemical differences were observed. In contrast to the case of the corresponding 2-methylquinolin-8-ylamido complex [ReOCl2(2-Me-8-HNqn)(PPh3)], substitution reaction of PPh3 to OPPh3 (=tfiphenylphosphine oxide) or pyridine did not take place, reflecting the high stability of the present 8-quinolinolato complexes. (c) 2005 Elsevier Ltd. All rights reserved., NATL INST MATERIALS SCIENCE
SCIENCE AND TECHNOLOGY OF ADVANCED MATERIALS, 2005年09月, ［査読有り］

Group 12 metal(II) complexes with 1-methylimidazoline-2(3H)-thione (mitH): correlation between crystal structure and physicochemical property
Y Matsunaga; K Fujisawa; N Amir; Y Miyashita; K Okamoto, The crystal structures of [ZnX2(mitH)(2)] (X = Cl (1), Br (2)), [ZnI(mitH)(3)] I ( 3), and [CdX2 (mitH)(2)] (X = Cl ( 4), Br ( 5), I ( 6)) (mitH = 1-methylimizadoline-2(3H)-thione) were determined by X-ray crystallography and all complexes were characterized by IR, far-IR, Raman, and UV-Vis absorption ( solid) spectroscopies. All complexes except 3, which have a different ZnIS3 coordination mode, have a distorted tetrahedral geometry with an MX2S2 coordination mode. Each pi-character of the C = S bonds ( from 37.7 to 45.4%) is smaller than that of free mitH (51.9%). Their M - S - C bond angles ( from 97 degrees to 109 degrees) support that the C = S bonds are not a full double bond. Their stretching vibration frequencies of M - S (300 - 320 cm(-1)) and M - X (229 - 290 cm(-1)) in both far-IR and Raman spectra show the lower energy shifts with increasing weight of metal(II) or halide ions. Similarly, some shifts ( from 275 nm for 1 to 293 nm for 6) are also observed in CT transition bands in UV-Vis absorption spectra., TAYLOR & FRANCIS LTD
JOURNAL OF COORDINATION CHEMISTRY, 2005年08月, ［査読有り］

Spectroscopic and DFT investigation of [M{HB(3,5-(i)Pr(2)pz)(3)}(SC6F5)] (M = Mn, Fe, Co, Ni, Cu, and Zn) model complexes: Periodic trends in metal-thiolate bonding
SI Gorelsky; L Basumallick; J Vura-Weis; R Sarangi; KO Hodgson; B Hedman; K Fujisawa; EI Solomon, A series of metal-varied [ML(SC6F5)] model complexes (where L = hydrotris(3,5-diisopropyl-1- pyrazolyl) borate and M = Mn, Fe, Co, Ni, Cu, and Zn) related to blue copper proteins has been studied by a combination of absorption, MCD, resonance Raman, and S K-edge X-ray absorption spectroscopies. Density functional calculations have been used to characterize these complexes and calculate their spectra. The observed variations in geometry, spectra, and bond energies are interpreted in terms of changes in the nature of metal-ligand bonding interactions. The metal 3d-ligand orbital interaction, which contributes to covalent bonding in these complexes, becomes stronger going from Mn(II) to Co(II) (the a contribution) and to Cu(II) (the g contribution). This change in the covalency results from the increased effective nuclear charge of the metal atom in going from Mn(II) to Zn(II) and the change in the 3d orbital populations (d(5)-> d(10)). Ionic bonding also plays an important role in determining the overall strength of the ML+-SC6F5- interaction. However, there is a compensating effect: as the covalent contribution to the metal-ligand bonding increases, the ionic contribution decreases. These results provide insight into the Irving-Williams series, where it is found that the bonding of the ligand being replaced by the thiolate makes a major contribution to the observed order of the stability constants over the series of metal ions., AMER CHEMICAL SOC
INORGANIC CHEMISTRY, 2005年07月, ［査読有り］

Zn(II) Complexes owith Aliphatic Thiolates. (Et₄N)[Zn(SAd)₃] and (Et₄N)₂[{Zn(ScHex)₂}₂(μ-ScHex)₂]
Yuki Matsunaga; Kiyoshi Fujisawa; Naoko Ibi; Nagina Amir; Yoshitaro Miyashita; Ken-ichi Okamoto, 表題に記した配位構造の異なる、チオラート亜鉛(II)錯体の合成・構造決定を行った。配位構造が性質に及ぼす影響について討論した。, CHEMICAL SOC JAPAN
Bull. Chem. Soc. Jpn., 2005年07月, ［査読有り］

Structural and physicochemical characterization of zinc(II) and cadmium(II) complexes with 1,4-dimethy-lhomopiperazine
Y Matsunaga; K Fujisawa; N Amir; Y Miyashita; K Okamoto, In order to know the relationship between structures and physicochemical properties of Group 12 metal(II) ions, the complexes with'simple'ligands, such as alkyl cyclic diamine ligand and halide ions, were synthesized by the reaction of 1,4-dimethylhomopiperazine (hp') with MX2 as metal sources (M = Zn, Cd; X = Cl, Br, I). The five structural types, [ZnX2 (hp') I (X = Cl (1), Br (2) and 1 (3)), [ZnX3 (Hhp')] (X = Cl (1') and Br (2')), [CdC1(2)(hp')](n) (4), [{CdCl2(Hhp')}(2)(mu-Cl-2)(2)] (4') and [{CdX(hp')}(2)(mu-X)(2)] (X = Br (5),1 (6)), were determined by X-ray analysis. The sizes of both metal(II) and halide ions and the difference in each other's polarizability influence each structure. All complexes were characterized by IR, far-IR, Raman and UV-Vis absorption spectroscopies. In the far-IR and Raman spectra, the typical nu(M-N) and nu(M-X) peaks clearly depend on the five structural types around 540-410 cm(-1) and 350-160 cm(-1) respectively. The UV-Vis absorption band energy around 204-250 nm also reflects each structural type. Copyright (c) 2005 John Wiley & Sons, Ltd., JOHN WILEY & SONS LTD
APPLIED ORGANOMETALLIC CHEMISTRY, 2005年06月, ［査読有り］

“Radical-Controlled” Oxidative Polymerization of Phenol: Comparison with that of 4-Phenoxyphenol
Hideyuki Higashimura; Kiyoshi Fujisawa; Masaaki Kubota; Shiro Kobayashi, チロシナーゼモデル錯体を用いて単純フェノールの酸化重合を行い、4-フェノキシフェノールとの反応の違いについて議論した。, JOHN WILEY & SONS INC
J. Poly. Sci., Part A: Polym. Chem., 2005年05月, ［査読有り］

Structural and spectroscopic characterization of first-row transition metal(II) substituted blue copper model complexes with hydrotris (pyrazolyl)borate
Y Matsunaga; K Fujisawa; N Ibi; Y Miyashita; K Okamoto, [CuL(SC6F5)] (1) (L = hydrotris (3,5-diisopropyl-1-pyrazolyl)borate anion) has been reported as a good model for blue copper proteins [Kitajima, N.; Fujisawa, K.; Tanaka, M.; Moro-oka, Y. J. Am. Chem. Soc. 1992, 114, 9232-9233]. To obtain more structural and spectroscopic insight, the first-row transition metal(II) substituted complexes of Cu(II) (1) to Mn(II) (2), Fe(II) (3), Co(II) (4), Ni(II) (5), and Zn(II) (6) were synthesized and their crystal structures were determined. These model complexes have a distorted tetrahedral geometry arising from the tripodal ligand L. The d value, which is defined by the distance from the N2S basal plane to the metal(II) ion, and the bond angles such as N-M-N and S-M-N are good indicators of these structural distortions. The obtained complexes were characterized by UV-vis absorption, EPR, NMR, far-IR, and FT-Raman spectroscopies and electrochemical and magnetic properties. In UV-vis absorption spectra, the sulfur-to-metal(II) CT bands and the d-d transtion bands are observed for 1 and 3-5. For 1, the strong sulfur to Cu(II) CT band at 663 nm, which is one of the unique properties of blue copper proteins, is observed.,The CT energies of the Fe(II) (3), Co(II) (4), and Ni(II) (5) complexes are shifted to higher energy (308 and 355 nm for 3, 311 and 340 nm for 4, 357 and 434 nm for 5) and are almost the same as the corresponding Co(II)- and Ni(II)-substituted blue copper proteins. In the far-IR spectra, three far-IR absorption bands for 2-6 at ca. 400, ca. 350, and ca. 310 cm(-1) are also observed similar to those for 1. Other properties are consistent with their distorted tetrahedral geometries., AMER CHEMICAL SOC
INORGANIC CHEMISTRY, 2005年01月, ［査読有り］

Dichloro[bis(1-methylimidazole-2)disulfide]zinc(II)
Y Matsunaga; K Fujisawa; N Amir; Y Miyashita; K Okamoto, The Zn center in [ZnCl2(L-S-S-L)], where L-S-S-L = bis(1-methylimidazole-2)disulfide, adopts a tetrahedral configuration defined by two Cl atoms and two N atoms from L-S-S-L, which was obtained by in situ oxidation of 1-methylimidazole-2-thione. Copyright (C) 2004 John Wiley Sons, Ltd., JOHN WILEY & SONS LTD
APPLIED ORGANOMETALLIC CHEMISTRY, 2005年01月, ［査読有り］

Linear-type S-Bridged trinuclear complexes with Ru-III ion and octahedral fac(S)-[M(aet)(3)] units (M = Rh-III, Ir-III; aet=2-aminoethethiolate)
N Amir; Y Miyashita; M Fujita; K Fujisawa; K Okamoto, The reactions of fac(S)-[M(aet)(3)] (M = Rh-III, Ir-III; aet = 2-aminoethanethiolate) with RuCl3&BULL; 3H(2)O in water gave trinuclear complexes, &UDelta;&ULambda;-, &UDelta;/&ULambda;-[Ru{Rh(aet}(3))(2)](3+) (1a, 1b.) and &UDelta;&ULambda;-, &UDelta;&UDelta;/&ULambda;&ULambda;-[Ru{Ir(aet)(3)}(2)](3+) (2a, 2b). The crystal structure of 2a(NO3)(3)&BULL; 3H(2)O revealed that the central Ru-III ion is coordinated by six S atoms from two fac(S)-[Ir(aet)(3)] units in an octahedral geometry, forming a linear-type S-bridged trinuclear structure. It was found that the UV-Visible (UV-Vis) spectral patterns of all complexes depend upon the terminal fac(S)-[M(aet)(3)] units. In the electro- and spectroelectrochemistry of these complexes, the Ir trinuclear complex showed a reversible [Ru{Ir(aet)(3)}(2)](3+/4+) redox process., TAYLOR & FRANCIS LTD
MOLECULAR CRYSTALS AND LIQUID CRYSTALS, 2005年, ［査読有り］

Synthetic models for active sites of reduced blue copper proteins: minimal geometric change between two oxidation states for fast self-exchange rate constants
K Fujisawa; K Fujita; T Takahashi; N Kitajima; Y Moro-oka; Y Matsunaga; Y Miyashita; K Okamoto, We have prepared two thiolato copper redox pairs ligated by HB(3,5-'Prpz)(3)(-) as models for blue copper proteins. The k(ex) value of the coordination number invariant Cu(II/I) couples is 51 times faster than that of the coordination number variant Cu(II/I) couples at -20 degreesC. We also discuss the electron-transfer process. (C) 2004 Elsevier B.V. All rights reserved., ELSEVIER SCIENCE BV
INORGANIC CHEMISTRY COMMUNICATIONS, 2004年11月, ［査読有り］

Manganese catalysts with scorpionate ligands for olefin polymerization
M Nabika; Y Seki; T Miyatake; Y Ishikawa; K Okamoto; K Fujisawa, The catalyst systems composed of hydrotris(pyrazolyl)borate (Tp) manganese and coactivators showed good activity for ethylene polymerization and ethylenea-alpha-olefin copolymerization. The activity of [MnCl(Tp)]/ Al(i-Bu)(3)/[Ph3C][B(C6F5)(4)] for ethylene/1-butene copolymerizations goes up to 1.6 x 10(7) g mol(cat)(-1) h(-1), giving ethylene-1-butene copolymer with a narrow molecular weight distribution (M-w/M-n = 1.8) and a high melting point (120 degreesC). This system is also active toward propylene and gives isotactic polypropylene with a triad mm fraction of 0.905., AMER CHEMICAL SOC
ORGANOMETALLICS, 2004年09月, ［査読有り］

Bis(μ-cystamine-κ⁴ N, S: S', N')bis[ (2-aminoethanethiolato-κ² N,S)iridium(III)];Tetrabromide Dihydrate
Mitsuharu Fujita; Yoshitaro Miyashita; Nagina Amir; Yasunori Yamada; Kiyoshi Fujisawa; Ken-ichi Okamoto, 表題の錯体の構造をX線解析により決定し、関連錯体との比較を行った。, BLACKWELL MUNKSGAARD
Acta Crystallogr. Sect. C, 2004年09月, ［査読有り］

Ab Initio Calculation on the Reaction Mechanism of “Radical-Controlled”Oxidative Polymerization of Phenols
Masaaki Kubota; Akinobu Shiga; Hideyuki Higashimura; Kiyoshi Fujisawa; Yoshihiko Moro-oka; Hiroshi Uyama; Shiro Kobayashi, ラジカル-コントロールにより反応制御した酸化重合反応の反応機構の解析を Ab Initio法により行った。, CHEMICAL SOC JAPAN
Bull. Chem. Soc. Jpn., 2004年04月, ［査読有り］

Copper(II) complexes with a novel tris(3,5-diisopropyl-1-pyrazolyl)methane ligand, [Cu(X-2){HC(3,5-(i)Pr(2)pz)(3)}](X=Cl and NO3)
K Fujisawa; T Ono; H Aoki; Y Ishikawa; Y Miyashita; K Okamoto; H Nakazawa; H Higashimura, The synthesis of a novel tris(3,5-diisopropyl-1-pyrazolyl)methane ligand, HC(3,5-(i)Pr(2)pz)(3), is described; the structures of chlorocopper(II) and nitratocopper(II) complexes with its ligand have been determined by X-ray crystallography and compared with those of the related copper(II) complexes with HB(3,5-(i)Pr(2)pz)(3)(-) (C) 2003 Elsevier B.V. All rights reserved., ELSEVIER SCIENCE BV
INORGANIC CHEMISTRY COMMUNICATIONS, 2004年03月, ［査読有り］

The most hindered hydrotris(pyrazolyl)borate ligand, X-ray structure of chlorocopper(II) complex: [Cu(Cl){HB(3-Ad-5-Pr(i)pz)(3)}] as compared with [Cu(Cl){HB(3-Bu-t-5-Pr(i)pz)(3)}]
K Fujisawa; N Tada; Y Ishikawa; H Higashimura; Y Miyashita; KI Okamoto, Admantyl substituted hydrotris(pyrazolyl)borate ligand, which is the most hindered in all the hydrotris(pyrazolyl)borate ligands, is newly synthesized. Two chlorocopper(II) complexes with [HB(3-Ad-5-Pr(i)pz)(3)](-) and [HB(3-Bu-t-5-Pr(i)PZ)(3)](-) were characterized by X-ray diffraction and some spectroscopic techniques. (C) 2003 Elsevier B.V. All rights reserved., ELSEVIER SCIENCE BV
INORGANIC CHEMISTRY COMMUNICATIONS, 2004年02月, ［査読有り］

Diazene complexes of copper: Synthesis, spectroscopic analysis, and electronic structure
K Fujisawa; N Lehnert; Y Ishikawa; K Okamoto, 架橋ジアゼン銅(I)錯体の構造を初めて決定した。詳細な分光解析を行うとともに、DFT計算によりその電子構造を明らかにした。, WILEY-V C H VERLAG GMBH
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION, 2004年, ［査読有り］

Crystal structure of pyrazolato-bridged copper(I) polynuclear complexes
K Fujisawa; Y Ishikawa; Y Miyashita; K Okamoto, We prepared a series of copper(I) polynuclear complexes bridged by three different alkyl substituted pyrazolate anions. From X-ray analysis, these differences reflected their molecular structures. These structural changes also reflected some properties in their IR, far-IR, UV-vis, and NMR spectra., CHEMICAL SOC JAPAN
CHEMISTRY LETTERS, 2004年01月, ［査読有り］

Selective Formation and Characterization of Oxorhenium(V) Complexes with 2-Methylquinolin-8-ylamido (Hamq). Interconversion between [ReOX₂(Hamq)(PPh₃) and [ReOX₂(Hamq)(OPPh₃)] (X =Cl, Br)　　　　　　　　　　　　　　　
Yoshitaro Miyashita; Md. Monirul Islam; Nagina Amir; Kiyoshi Fujisawa; Ken-ichi Okamoto, ポリアミンポリカルボン酸を配位子とする多核チタン(IV)錯体を合成し、その構造を決定するとともに、その性質を明らかにした。
Chem. Lett., 2004年, ［査読有り］

Syntheses of linear-type S-bridged trinuclear complexes composed of heavy d⁶metal ions and 2-aminoethanethiolate: Comparative characterization by X-ray diffraction, spectroscopy and electrochemistry
Mahboob, N.; Miyashita, Y.; Yamada, Y.; Fujisawa, K.; Okamoto, K.-I., Ir(III)、Rh(III)を含む錯体配位子とRh(III)イオンを反応させることにより得られる錯体の光学分割を行い、得られた錯体の構造を決定するとともに、錯体の分光学的性質の検討を行った。
Inorganica Chimica Acta, 2004年, ［査読有り］

Oxygen Activation by Nonchem Iron（Ⅱ） Complexes: α-Keto Caboxylate versus Carboxylate
Mark P. Mehn; Kiyoshi Fujisawa; Eric L. Hegg; Lawreance Que, J, α-ケト酸が配位した鉄(II)錯体の酸素活性化機構に関して詳細な検討を行った。鉄(II)錯体と酸化生成物の構造も決定した。

酸化酵素の反応機構に関する討論も行った。, AMER CHEMICAL SOC
J. Am. Chem. Soc., 2003年07月, ［査読有り］

Asymmetric conjugate addition reaction using pyrazole derivatives as a chiral catalyst
C Kashima; H Yokoyama; S Shibata; K Fujisawa; T Nishio, The conjugate addition of Grignard reagent (2) onto 1-(alpha,beta-unsaturated)acyl 3,5-dimethylpyrazole (1) was enantioselectively catalyzed by the copper complex from cuprous compounds and 3-phenyl-l-menthopyrazole (3)., WILEY-BLACKWELL
JOURNAL OF HETEROCYCLIC CHEMISTRY, 2003年07月, ［査読有り］

UV-Vis absorption and CD spectroelectrochemical studies on S-bridged polycobalt(III) complexes with 2-aminoethanethiolate or L-cysteinate
Y Miyashita; H Yoshida; T Sato; Y Yamada; K Fujisawa; K Okamoto, The UV-vis spectroelectrochemical properties of S-bridged tricobalt(III) complexes [Co-III{Co-III(aet or L-cys)(3)}(2)](3+ or 3-) and dicobalt(III) complexes [Co-III{Co-III(aet or L-cys)(3)}(dien)](3+ or 0) (aet = 2-aminoethanethiolate, L-cys = L-cysteinate, then = diethylenetriamine) were investigated using a thin-layer quartz cell with a platinum mesh working electrode. The absorption spectroelectrochemical measurements for the tricobalt(M) complexes indicated that a two-electron reduction proceeds through pseudo two-steps, (CoCoCoIII)-Co-III-Co-III --> (CoCoCoIII)-Co-III-Co-II --> (CoCoCoII)-Co-III-Co-II for the aet complex, while through pseudo one-step for the L-cys complex. The CD spectroelectrochemical measurements demonstrated that the optically active isomer (DeltaDelta form) of the aet tricobalt(III) complex loses chirality during the one-electron reduction, whereas the Delta(LLL)Delta(LLL) isomer of the L-cys tricobalt(III) complex is reduced with an inversion of configuration, to form the Delta(LLL)Delta(LLL) isomer. The Delta(LLL)Delta(LLL) isomer is reduced with a retention of configuration. The aet and L-cys dicobalt(III) complexes were converted to the corresponding tricobalt(III) complexes by electrochemical reduction, accompanied by the release of the Co(II) ion and then ligand. It was also elucidated that this conversion occurred with a retention of configuration., CHEMICAL SOC JAPAN
BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN, 2003年06月, ［査読有り］

Spectroscopy and bonding in side-on and end-on Cu-2(S-2) cores: Comparison to peroxide analogues
P Chen; K Fujisawa; ME Helton; KD Karlin; EI Solomon, Spectroscopic methods combined with density functional calculations were used to study the disulfide-Cull bonding interactions in the side-on mu-eta(2):eta(2)-bridged Cu-2(S-2) complex, [{Cu-II[HB(3,5-Pr(2)(i)pz)(3)]}(2)-(S-2)], and the end-on trans-mu-1,2-bridged Cu-2(S-2) complex, [{Cu-II(TMPA)}(2)(S-2)](2+), in correlation to their peroxide structural analogues. Resonance Raman shows weaker S-S bonds and stronger Cu-S bonds in the disulfide complexes relative to the O-O and Cu-O bonds in the peroxide analogues. The weaker S-S bonds come from the more limited interaction between the S(3)p orbitals relative to that of the O(2)s/p hybrid orbitals. The stronger Cu-S bonds result from the more covalent Cu-disulfide interactions relative to the Cu-peroxide interactions. This is consistent with the higher energy of the disulfide valence level relative to that of the peroxide. The ground states of the side-on Cu-2(S-2)/Cu-2(O-2) complexes are more covalent than those of the end-on Cu-2(S-2)/Cu-2(O-2) complexes. This derives from the larger sigma-donor interactions in the side-on mu-eta(2):eta(2) structure, which has four Cu-disulfide/peroxide bonds, relative to the end-on trans-mu-1,2 structure, which forms two bonds to the Cu. The larger disulfide/peroxide sigma-donor interactions in the side-on complexes are reflected in their more intense higher energy disulfide/peroxide to Cu charge transfer transitions in the absorption spectra. The large ground-state covalencies of the side-on complexes result in significant nuclear distortions in the ligand-to-metal charge transfer excited states, which give rise to the strong resonance Raman enhancements of the metal-ligand and intraligand vibrations. Particularly, the large covalency of the Cu-disulfide interaction in the side-on Cu-2(S-2) complex leads to a different rR enhancement profile, relative to the peroxide analogues, reflecting a S-S bond distortion in the opposite directions in the disulfide/peroxide pi*(sigma) to Cu charge transfer excited states. A ligand sigma* back-bonding interaction exists only in the side-on complexes, and there is more sigma* mixing in the side-on Cu-2(S-2) complex than in the side-on Cu-2(O-2) Complex. This sigma* back-bonding is shown to significantly weaken the S-S/O-O bond relative to that of the analogous end-on complex, leading to the low v(S-S)/v(O-O) vibrational frequencies observed in the resonance Raman spectra of the side-on complexes., AMER CHEMICAL SOC
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 2003年05月, ［査読有り］

"Radical-controlled" oxidative polymerization of phenols
H Higashimura; K Fujisawa; Y Moro-oka; M Kubota; A Shiga; H Uyama; S Kobayashi, KODANSHA LTD
SCIENCE AND TECHNOLOGY IN CATALYSIS 2002, 2003年, ［査読有り］

Reaction path to phenol coupling with copper complex
M Kubota; H Higashimura; A Shiga; K Fujisawa; H Uyama; S Kobayashi, KODANSHA LTD
SCIENCE AND TECHNOLOGY IN CATALYSIS 2002, 2003年, ［査読有り］

Spectroscopic and Electronic Structure Studied of the Diamagnetic Side-On Cu^Ⅱ-Superoxo Complex Cu(O₂)HB(3-R-5-iPrpz)₃: Antiferromagnetic Coupling vs. Covalent Delocalization
Peng Chen; David E. Root; Cecelia Campochiaro; Kiyoshi Fujisawa; Edward I. Solomon, 単核スーパーオキソ銅(II)錯体の詳細な分光解析を行うとともに、DFT計算によりその電子構造を明らかにした。反強磁性相互作用の由来について討論を行った。酸化酵素の反応機構に関する討論も行った。, AMER CHEMICAL SOC
J. Am. Chem. Soc., 2003年01月, ［査読有り］

Electronic structure and reactivity of high-spin iron-alkyl- and -pterinperoxo complexes
N Lehnert; K Fujisawa; EI Solomon, The spectroscopic properties and electronic structure of the four-coordinate high-spin [Fe-III(L3)((OOBu)-Bu-t)](+) complex (1; L3 = hydrotris(3-tert-butyl-5-isopropyl-1-pyrazolyl)borate; Bu-t = tert-butyl) are investigated and compared to the six-coordinate high-spin [Fe(6-Me(3)TPA)(OHx)((OOBu)-Bu-t)](x+) system (TPA = tris(2-pyridylmethyl)amine, x = 1 or 2) studied earlier [Lehnert, N.; Ho, R. Y. N.; Que, L., Jr.; Solomon, E. I. J. Am. Chem. Soc. 2001, 123, 12802-12816]. Complex 1 is characterized by Raman features at 889 and 830 cm(-1) which are assigned to the O-O stretch (mixed with the symmetric C-C stretch) and a band at 625 cm-1 that corresponds to nu(Fe-O). The UV-vis spectrum shows a charge-transfer (CT) transition at 510 nm from the alkylperoxo pi(nu)(*) (v = vertical to C-O-O plane) to a d orbital of Fe(Ill). A second CT is identified from MCD at 370 nm that is assigned to a transition from pi(h)(*) (h = horizontal to C-O-O plane) to an Fe(III) d orbital. For the TPA complex the pi(nu)(*) CT is at 560 nm while the pi(h)(*) CT is to higher energy than 250 nm. These spectroscopic differences between four- and six-coordinate h Fe(III)-OOR complexes are interpreted on the basis of their different ligand fields. In addition, the electronic structure of Fe-OOPtn complexes with the biologically relevant pterinperoxo ligand are investigated. Substitution of the tert-butyl group in 1 by pterin leads to the corresponding Fe(III)-OOPtn species (2), which shows a stronger electron donation from the peroxide to Fe(III) than 1. This is related to the lower ionization potential of pterin. Reduction of 2 by one electron leads to the Fe(II)-OOPtn complex (3), which is relevant as a model for potential intermediates in pterin-dependent hydroxylases. However, in the four-coordinate ligand field of 3, the additional electron is located in a nonbonding d orbital of iron. Hence, the pterinperoxo ligand is not activated for heterolytic cleavage of the O-O bond in this system. This is also evident from the calculated reaction energies that are endothermic by at least 20 kcal/mol., AMER CHEMICAL SOC
INORGANIC CHEMISTRY, 2003年01月, ［査読有り］

Selective formation and characterization of oxorhenium(V) complexes with 2-methylquinolin-8-ylamido (Hamq). Interconversion between [ReOX2(Hamq)(PPH3)] and [ReOX2(Hamq)(OPPH3)] (X = Cl, Br)
Ohashi, T.; Miyashita, Y.; Yamada, Y.; Fujisawa, K.; Okamoto, K.-I., オキソレニウム(V)を含む錯体と8-アミノキノリン誘導体との反応により生成する錯体の構造と分光学的性質の検討を行った。
Bulletin of the Chemical Society of Japan, 2003年

Spectroscopic comparison of the five-coordinate [Cu(SMeIm)(HB(3,5-iPr(2)pz)(3))] with the four-coordinate [Cu(SCPh3)(HB(3,5-iPr(2)pz)(3))]: effect of coordination number increase on a blue cop per type site
L Basumallick; SD George; DW Randall; B Hedman; KO Hodgson; K Fujisawa; EI Solomon, A variety of spectroscopic techniques have been applied to characterize and compare two model complexes with relevance to red and blue copper centers in metalloproteins, [Cu(SMeIm)(HB(3,5-iPr(2)pz)3)] (1) and [Cu(SCPh3)(HB(3,5-iPr(2)pz)3)] (2), which are five- and four-coordinate, respectively. The key spectral differences in low temperature absorption and magnetic circular dichroism. (MCD) include an increase in the Ssigma-->Cu charge transfer (CT) band intensity at 370 nm and a decrease in the absorption intensity at similar to570 nm for the Spi-->Cu CT. The energies of the d-->d transitions in 1 are increased relative to 2 reflecting a more tetragonal geometry and a stronger ligand field. S K-edge X-ray absorption spectroscopy (XAS) measurements demonstrate a less covalent thiolate Cu interaction in the HOMO of 1 (15% Sp) compared to 2 (52% Sp). XAS at the Cu L-edge indicates that the Cu d-character in the HOMO of 1 has increased relative to that of 2. The electronic perturbation resulting from the increased coordination number has been evaluated. The thiolate rotates in the NNS plane resulting in increased sigma overlap with the Cu. Additionally, the Cu-S bond length increases. The associated reduced covalency of the thiolate can contribute to the function of perturbed blue copper sites in proteins. (C) 2002 Elsevier Science B.V. All rights reserved., ELSEVIER SCIENCE SA
INORGANICA CHIMICA ACTA, 2002年09月, ［査読有り］, ［招待有り］

Crystal structures, electronic absorption and reflectance spectral behaviors, and electrochemical properties of five-coordinated chlorocopper(II) complexes with 5,6-disubstituted-1,10-phenanthroline
Y Yamada; H Sakurai; Y Miyashita; K Fujisawa; K Okamoto, The five-coordinated geometries around the Cu(II) centers in [CuCl(dmphen)(2)]PF6 (1; dmphen = 5,6-di-methyl-1,10-phenanthroline) and [CuCl(phendione)(2)]PF6 (.) H2O (2; phendione = 1,10-phenanthroline-5,6-dione) are distorted square-pyramidal in contrast to the distorted trigonal-bipyramidal [CuCl(phen)(2)]PF6 (phen = 1, 10-phenanthroline), reflecting introductions of substituents into the 5- and 6-positions on phen. It has been found that these geometries in I and 2 are considerably dependent on the interactions between the pi-electronic systems of the phen frameworks. The diffuse reflectance spectra significantly reflect geometrical differences of 1 and 2 from [CuCl(phen)(2)]PF6. The electronic absorption spectra suggest that the geometries of 1 and 2 in solution are similar to those in the crystalline state, while the geometry of [CuCl(phen)2]PF6 seems to be changed from distorted trigonal-bipyramid to square-pyramid. The electrochemical experiments indicate that the redox properties of these complexes are appreciably influenced by the electronic characters of the substituents on the phen frameworks. (C) 2002 Elsevier Science Ltd. All rights reserved., PERGAMON-ELSEVIER SCIENCE LTD
POLYHEDRON, 2002年09月

Novel Alkoxo-Bridged Lanthanide(III) Dinuclear Complexes: Crystal Structure of Na₄[Yb₂(μ-dpta-O)₂] (N₄dpta-OH = 1,3-Diamino-2-hydroxypropane-N, N, N' ,N'-tetraacetic acid)
Yoshitaro Miyashita; Masateru Sanada; Yasunori Yamada; Kiyoshi Fujisawa; Ken-ichi Okamoto, N4型多カルボン酸配位子とランタノイド(III)イオンを反応させることにより得られる錯体の立体化学について検討を行った。, CHEMICAL SOC JAPAN
Chem. Lett., 2002年08月, ［査読有り］

Characterization and Electrochemical Properties for Rhenium(III) Ion Incorporated into Linear-Type S-Bridged Trinuclear Complexes. Crystal Structures of ΔΛ- and ΔΔ/ΛΛ-[Re{Ir(aet)₃}₂]³⁺ (aet = 2-aminoethanethiolate)
Nagina Mahboob; Yoshitaro Miyashita; Yasunori Yamada; Kiyoshi Fujisawa; Ken-ichi Okamoto, Ir(III)を含む錯体配位子とRe(VII)イオンを反応させることにより得られる直線型硫黄架橋3核錯体の立体化学、性質、電気化学的挙動について検討を行った。, PERGAMON-ELSEVIER SCIENCE LTD
Polyhedron, 2002年08月, ［査読有り］

Optically Active S-Bridged Co^IIIM (M = Pt^II, Hg^II, Au^I) Polynuclear Complexes Derived from ΔΔ-[Ni{Co(aet)₂(R-pn)}₂]⁴⁺ (aet = 2-Aminoethanethiolate, R-pn = (R
Yasunori Yamada; Yoshitaro Miyashita; Kiyoshi Fujisawa; Ken-ichi Okamoto, CoNiCoタイプの直線型硫黄架橋3核錯体と金属イオンとの反応によりから得られる光学活性多核錯体の構造を決定するとともに、分光学的性質の検討を行った, CHEMICAL SOC JAPAN
Bull. Chem. Soc. Jpn., 2002年05月, ［査読有り］

Syntheses, stereochemistry, reactivity, and some properties of sulfur-bridged cobalt(III)-cadmium(II) polynuclear complexes derived from mononuclear cobalt(III) complex with D-penicillaminate
Y Yamada; M Tsumita; A Hirano; Y Miyashita; K Fujisawa; K Okamoto, A reaction of the octahedral bidentate metalloligand, trans(N)-[CO(D-pen)(2)](-) (D-pen = D-penicillaminate) with Cd(-NO3)(2) or Cd(ClO4)(2) gave a novel S-bridged trinuclear complex, [Cd(H2O){Co(D-pen)(2)}(2)]. In this complex molecule, the central Cd atom is surrounded by four S atoms from two [Co(D-pen)(2)](-) units and one O atom of a H2O molecule to form a distorted five-coordinated geometry. Each of two terminal [CO(D-pen)(2)](=) units takes an approximatefy octahedral geometry and has a similar trans(N) geometry to that of the starting material, On the other hand. the reaction of trans(N)-[CO(D-pen)(2)](-) with CdCl2 in the molar ratio of 1:1 gave an S-bridged dinuclear complex, [CdCl{Co(D-pen)(2)}(H2O)(m)].nH(2)O (m + n = 4) (2). The reactivity Of trans(N)-[Co(D-pen)(2)](-) toward CdCl2 is significantly influenced by the ratio of two components, and the formation of a similar trinuclear species to 1 is also suggested under the condition with excess amount of trans(N)-[Co(D-pen)(2)](-). Some spectrochemical properties of these complexes are also discussed in relation to their structures. (C) 2002 Elsevier Science B.V. All rights reserved., ELSEVIER SCIENCE SA
INORGANICA CHIMICA ACTA, 2002年04月, ［査読有り］

Spectroscopic Comparison of the 5-Coordinate [Cu(SMeIm)(HB(3, 5-iPr₂pz)₃] with the 4-Coordinate [Cu(SCPh₃)(HB(3, 5-iPr₂pz)₃] : Effect of Coordination Number Increase on a Blue Copper Type Site.　　　　　　　　　　　　　　　
Lipika Basumallick; Serena DeBeer George; David W. Randall; Britte Hedman; Keith O. Hodgson; Kiyoshi Fujisawa; Edward I. Solomon, 5配位チオラート銅(II)錯体を合成し、構造決定した。対応する4配位チオラート銅(II)錯体との分光学的性質の比較を詳細に行い、配位数の増加がどのような構造や性質に影響を与えるか討論した。
Inorg. Chim. Acta (K. Wieghardt special volume), 2002年, ［査読有り］, ［招待有り］

anti-Bis(μ-2-ammonioethanethiolato-κ²S:S)bis[dichloropalladium(II)]dehydrate
Yoshitaro Miyashita; Satoshi Arai; Yasunori Yamada; Kiyoshi Fujisawa; Ken-ichi Okamoto, 表題の錯体の構造をX線解析により決定し、関連錯体との比較を行った。, MUNKSGAARD INT PUBL LTD
Acta Crystallogr. Sect. C., 2001年12月, ［査読有り］

Electrolytic partial fluorination of organic compounds. 54.1 Anodic mono- and trifluorination of thiochroman-4-one derivatives and the factors affecting product selectivity
K. M. Dawood; H. Ishii; K. Fujisawa; T. Fuchigami, Anodic fluorination of (E)-3-benzylidene-2,3-dihydrothiochroman-4-one and 3-benzyl-1-thiochromone derivatives under a variety of electrolytic conditions was found to provide selectively or exclusively the same fluorinated products: (E)-3-benzylidene-2,3-dihydro-2-fluorothiochroman-4-ones. In addition, di- and trifluorinated derivatives were also obtained depending on the starting heterocycles and electrolytic conditions. The factors affecting the product selectivity were also examined.
Journal of Organic Chemistry, 2001年10月19日, ［査読有り］

Electroytic partial fluorination of organic compounds. 52. Regio- and diastereoselective anodic fluorination of thiazolidines
D Baba; H Ishii; S Higashiya; K Fujisawa; T Fuchigami, Anodic fluorination of N-benzoyl, N-acethyl-, and N-formylthiazolidine derived from L-cysteine was carried out in dimethoxyethane (DME) and acetonitrile containing various supporting fluoride salts using an undivided cell. Highly regioselective fluorination proceeded to provide the corresponding 5-monofluorinated thiazolidine derivatives in good yields in DME, and the diastereoselectivitiy was moderate to high regardless of the supporting fluoride salts. The diastereoselectivitiy of the fluorination was greatly affected by the bulkyness of the subsitituent on the nitrogen atom, and N-benzoylthiazolidine gave much higher diastereoselectivity compared with N-formyl derivative. The fluorination of the thiazolidines was not achieved by commercially available fluorinating reagents such as N-fluoropyridinium salts., AMER CHEMICAL SOC
JOURNAL OF ORGANIC CHEMISTRY, 2001年10月, ［査読有り］

Crystal Structure and Spectroscopic Characterization of Linear-Type S-Bridged Trinuclear Complexes Δ- and ΔΔ/ΛΛ-[Re^III{RhIII(aet)₃}]³⁺ (aet = 2-Aminoethanethiolate)
Yoshitaro Miyashita; Nagina Mahboob; Satoko Tsuboi; Yasunori Yamada; Kiyoshi Fujisawa; Ken-ichi Okamoto, Rh(III)を含む錯体配位子とRe(VII)イオンを反応させることにより得られる直線タイプ硫黄架橋3核錯体の構造を決定するとともに、分光学的性質の検討を行った。, CHEMICAL SOC JAPAN
Bull. Chem. Soc. Jpn., 2001年07月, ［査読有り］

Structural effects on nitratocopper(II) complexes of tris (pyrazolyl)borates
K Fujisawa; Y Miyashita; Y Yamada; K Okamoto, Some structural influences on nitratocopper(II) complexes ligated by a series of hydrotris(pyrazolyl)borates are described. The 5-position of pyrazole rings as well as the 3-position is important to provide coordination structure., CHEMICAL SOC JAPAN
BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN, 2001年06月, ［査読有り］

fac-trichloro(quinolin-8-ylimido-N,N ')(triphenylphosphine-P)rhenium(V)
Y Miyashita; N Mahboob; S Tsuboi; Y Yamada; K Fujisawa; K Okamoto, The Re atom in [Re(C9H6N2)Cl-3 (C18H15P)] is octahedrally coordinated by three Cl atoms in facial positions, two N atoms from 8-imidoquinoline (imq) and one P atom from triphenylphosphine. The Re-N(imido) distance [1.760 (9) and 1.772 (8) Angstrom] for imq is very short and implies double-bond character. The trans influence of the P atom is indicated. Intra- and intermolecular pi-pi interactions between the pi -rings in the complex are also observed., MUNKSGAARD INT PUBL LTD
ACTA CRYSTALLOGRAPHICA SECTION C-CRYSTAL STRUCTURE COMMUNICATIONS, 2001年05月, ［査読有り］

Synthesis, characterization and reactivity of linear-type S-bridged trinuclear complexes containing vanadium(III) ion. Crystal structures of[VIII{M(aet)3}2](ClO4) 3 (M = RhIII, IrIII; aet = 2-aminoethanethiolate)　　　　　　　　　　　　　　　
Y. Miyashita; M. Hamajima; Y. Yamada; K. Fujisawa; K. I. Okamoto, Reactions of fac(S)-[M(aet)3] (M = RhIII, IrIII
aet = 2-aminoethanethiolate) with an excess of VCl3 gave linear-type S-bridged trinuclear complexes [VIII{M(aet)3}2]3+ (M = RhIII 1, IrIII 2). The ΔΛ isomers (1a(ClO4)3 and 2a(ClO4)3) were selectively crystallized and their structures were determined by X-ray diffraction. Both the complex cations consist of two terminal fac(S)-[M(aet)3] units and a central vanadium atom, which is situated in an octahedral environment with a VIIIS6 chromophore. The Ir complex 2a was also formed by using VIVOCl2 instead of VIIICl3 in a redox reaction, whereas the Rh complex 1a was not formed by a similar method. The optically active isomer (ΛΛ-1b) of the Rh complex was selectively obtained by using Λ-fac(S)-[Rh(aet)3], and characterized by IR, UV-VIS absorption and CD spectra. All the obtained complexes exhibit a unique strong absorption band at ca. 18 × 103 cm-1. Stability and reactivity relating to V-S bond cleavage for the complexes were investigated using UV-VIS absorption spectroscopic methods. These studies show first order decomposition or metal exchange. While 2a has weaker V-S bonds than 1a (from the X-ray analyses), the former is considerably more stable in water than the latter. Cyclic voltammograms of 1a and 2a in water show only irreversible oxidation and reduction waves including VIV/III and VIII/II processes. The V(III) ions in the S-bridged trinuclear structures exhibit a lower magnetic moment (2.59 μB for 1a and 2.27 μB for 2a) at room temperature than the spin-only value for a d2 electronic configuration.
Journal of the Chemical Society, Dalton Transactions, 2001年

Synthesis, characterization and reactivity of linear-type S-bridged trinuclear complexes containing vanadium(III) ion. Crystal structures of [V-III{M(aet)(3)}(2)](ClO4)(3) (M = Rh-III, Ir-III; aet=2-aminoethanethiolate)
Y Miyashita; M Hamajima; Y Yamada; K Fujisawa; K Okamoto, Reactions of fac(S)-[M(aet)(3)] (M=Rh-III, Ir-III; aet=2-aminoethanethiolate) with an excess of VCl3 gave linear-type S-bridged trinuclear complexes [V-III{M(aet)(3)}(2)](3+) (M=Rh-III 1, Ir-III 2). The Delta Lambda isomers (1a(ClO4)(3) and 2a(ClO4)(3)) were selectively crystallized and their structures were determined by X-ray diffraction. Both the complex cations consist of two terminal fac(S)-[M(aet)(3)] units and a central vanadium atom, which is situated in an octahedral environment with a (VS6)-S-III chromophore. The Ir complex 2a was also formed by using (VOCl2)-O-IV instead of (VCl3)-Cl-III in a redox reaction, whereas the Rh complex 1a was not formed by a similar method. The optically active isomer (Lambda Lambda -1b) of the Rh complex was selectively obtained by using Lambda -fac(S)-[Rh(aet)(3)], and characterized by IR, UV-VIS absorption and CD spectra. All the obtained complexes exhibit a unique strong absorption band at ca. 18x10(3) cm(-1). Stability and reactivity relating to V-S bond cleavage for the complexes were investigated using UV-VIS absorption spectroscopic methods. These studies show first order decomposition or metal exchange. While 2a has weaker V-S bonds than 1a (from the X-ray analyses), the former is considerably more stable in water than the latter. Cyclic voltammograms of 1a and 2a in water show only irreversible oxidation and reduction waves including V-IV/III and V-III/II processes. The V(III) ions in the S-bridged trinuclear structures exhibit a lower magnetic moment (2.59 mu (B) for 1a and 2.27 mu (B) for 2a) at room temperature than the spin-only value for a d(2) electronic configuration., ROYAL SOC CHEMISTRY
JOURNAL OF THE CHEMICAL SOCIETY-DALTON TRANSACTIONS, 2001年, ［査読有り］

Synthesis, crystal structure, and some spectrochemical properties of S-bridged hexanuclear zinc(II) complex with 2-aminoethane-thiolate: Formation of Zn3S3- and Zn4S4-cyclic cores
Y Yamada; Y Miyashita; K Fujisawa; K Okamoto, The reaction of [Zn(aet)(2)] (aet = 2-aminoethanethiolate) with Zn(ClO4)(2). 6H(2)O in aqueous acetonitrile gave an S-bridged hexanuclear complex, [{Zn(aet)}(4){Zn(aet)(2)}(2)](4+), accompanied by the ligand-transfer of act from [Zn(aet)(2)] units to Zn2+ ions. In the hexanuclear complex, all of the Zn and S atoms are included in the Zn3S3- and/or Zn4S4-cyclic structures., CHEMICAL SOC JAPAN
BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN, 2001年01月, ［査読有り］

Spectroscopic and electronic structural studies of blue copper model complexes. 1. Perturbation of the thiolate-Cu bond
DW Randall; SD George; B Hedman; KO Hodgson; K Fujisawa; EI Solomon, A tris(pyrazolyl)hydroborate triphenylmethylthiolate Cu(II) model complex (1) that reproduces structural and spectroscopic features of active sites of blue Cu proteins is characterized using low-temperature absorption, magnetic circular dichroism (MCD), X-ray absorption (XAS), and resonance Raman (rR) spectroscopies combined with DFT calculations to define its electronic structure. The electronic structure of 1 is further related to the oxidized Cu site in plastocyanin. The key spectral differences relative to plastocyanin include an increase in the intensity of the S p pi --> Cu CT band and a decrease in the absorption intensity at similar to 450 nm. The energies, of d --> d transitions in 1 decrease relative to plastocyanin, which reflects the more tetrahedral geometry of 1. S K-edge XAS measurements demonstrate a more covalent thiolate interaction in the HOMO of 1 (52% S p) than in plastocyanin (38% S p). The effects of the high thiolate;covalency drl:the absorption and Raman spectral features for I are evaluated. Additional changes in the absorption spectrum of 1 relative to plastocyanin in the similar to 450 nm and the near-infrared regions are due to differences in the electronic structure of the nitrogen ligands associated with the change from imidazole to pyrazole. Finally, XAS measurements at the Cu L- and K-edges indicate that the effective nuclear charge of Cu in I is higher than in plastocyanin, which likely results from misdirection of the ligating orbitals in the constrained tris(pyrazolyl)hydroborate Ligand system. This reduces the donor interaction of this ligand with the copper which increases I : the covalency of the thiolate-Cu bond and can contribute to the electron-transfer properties of the blue copper site., AMER CHEMICAL SOC
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 2000年11月, ［査読有り］

M-S Vibrational Study in Three-Coordinate Thiolato Compounds (NEt₄)₂[M(SC₆H₄-p-X)₃] and (NEt₄)₂[M₄(μ-SC₆H₄-p-Cl)₆] : M=Cu(Ⅰ) and Ag(Ⅰ)
Kiyoshi Fujisawa; Sadako Imai; Syusuke Suzuki; Yoshihiko Moro-oka; Yoshitaro Miyashita; Yasunori Yamada; Ken-ichi Okamoto, パラ置換体のベンゼンチオラート錯体を銅(I)、銀(I)イオンを用いて合成し、M-S伸縮振動に関して詳細な検討を行った。その結果、この手法は金属-配位モードの類推に有用であることを明らかとした。, ELSEVIER SCIENCE INC
J. Inorg. Biochem., 2000年11月, ［査読有り］

New crystalline polymers: poly(2,5-dialkyl-l,4phenylene oxide)s
H Higashimura; K Fujisawa; Y Moro-oka; S Namekawa; M Kubota; A Shiga; H Uyama; S Kobayashi, New heat-reversibly crystalline poly-(alkylated phenylene oxide)s are described the oxidative polymerization of 2,5-dimethylphenol catalyzed by (1,4,7-triisopropyl-1,4,7-triazacyclononane) copper dichloride produced poly (2,5- dimethly-1,4-phenylene oxide), which showed heat-reversible crystallinity with a high melting point at ca. 300 degreesC, although the isomeric polymer, poly(2,6-dimethyl-1,4-phenylene oxide), never recrystallizes once melted. The polymerization of 2,5-diethylphenol and 2,5-dipropylphenol gave the polymers consisting of 1,4-phenylene oxide units; the latter polymer possessed heat-reversible crystallinity, however, the former one did not., WILEY-V C H VERLAG GMBH
MACROMOLECULAR RAPID COMMUNICATIONS, 2000年11月, ［査読有り］

Spectroscopic and theoretical studies of mononuclear copper(II) alkyl- and hydroperoxo complexes: Electronic structure contributions to reactivity
P Chen; K Fujisawa; EI Solomon, Spectroscopic studies combined with calculations are used to describe the electronic structure and vibrational properties of mononuclear four-coordinate end-on alkylperoxo and hydroperoxo Cu(II) complexes. EPR defines a Cu x(2)-y(2) ground state with similar to 62% Cu character. From absorption, MCD, and resonance Raman spectroscopies, the main bonding interaction between the alkyl(hydro)peroxide and Cu(LI) is found to involve the pi -donation of the alkyl(hydro)peroxide pi*(v) into the Cu x(2)-y(2) orbital, which dominates the observed spectroscopic features, producing an intense absorption band at similar to 16 600 cm(-1) (similar to 600 nm). On the basis of the vibrational frequencies, isotope shifts, and normal coordinate analyses, the dominant vibrations of the alkyl(hydro)peroxo complexes are assigned and the Cu-O and O-O force constants are determined. The observed strong Cu-O bond and the large alkyl(hydro)peroxide-to-Cu(II) charge donation are ascribed to the low coordination number of Cu and the distorted T-d ligand field. The observed strong O-O bond mainly derives from polarization by the alkylcarbon/proton. The unoccupied peroxide sigma* orbital is also greatly stabilized in energy, and the complexes are activated for electrophilic attack. Experimentally calibrated density functional calculations, coupled with frontier molecular orbital theory, are employed to obtain insight into the reactivity of these model complexes. Mechanisms of electrophilic attack, O-O bond cleavage, and H atom abstraction are evaluated, and their relevance to dopamine beta -monooxygenase and peptidylglycine alpha -hydroxylating monooxygenase reactivities is considered., AMER CHEMICAL SOC
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 2000年10月, ［査読有り］

Structural Characteristics of S-Bridged Trinuclear Complexes [{Pd(terpy)}₂{Pd(aet)₂}]⁴⁺ (terpy = 2,2':6',2”-Terpyridine, aet = 2-Aminoethanethiolate): Effects of Counter Anions and Solvent on Intra- and Intermolecular Stac
Yasunori Yamada; Kiyoshi Fujisawa; Ken-ichi Okamoto, 平面型Pd(II)錯体とPd(II)錯体配位子との反応により得られる硫黄架橋3核Pd(II)錯体の構造を決定するとともに、錯体の分光化学的検討を行った。特に用いた対イオンと溶媒により、スタッキング相互作用に影響が見られた。, CHEMICAL SOC JAPAN
Bull. Chem. Soc. Jpn., 2000年10月, ［査読有り］

Syntheses, crystal structures, and some spectrochemical properties of S-bridged tetranuclear complexes with stacking arrangements composed of planar palladium(II) units
Y Yamada; K Fujisawa; K Okamoto, The reaction of [Pd(aet)(2)] (aet = 2-aminoethanethiolate) with [Pd(NO3)(2)(diimine)] (diimine = 2,2'-bipyridine (bpy), 4,4'-dimethyl-2,2'-bipyridine (dmbpy), 1,10-phenanthroline (phen), 4,7-dimethyl-1,10-phenanthroline (dmphen)) gave a new type of S-bridged tetranuclear complex [{Pd(diimine)}(2){Pd(aet)(2)}(2)](4+). The crystal structures of these complexes were determined by X-ray crystallography. In these complexes, the two intramolecular diimine moieties are aligned so as to overlap each other and the PdN2S2 planes in the {Pd(aet)(2)} units are almost perpendicular to those in the {Pd(diimine)} moieties. In the case of diimine = bpy and dmbpy, furthermore, the complex cations exist in the dimeric structure with a coplanar stacking arrangement, in which the diimine moieties of the two distinct complex cations are antiparallel to each other. In the case of diimine = phen and dmphen, on the other hand, the complex cations exist in the linear-chainlike structure with an alternate coplanar stacking arrangement, in which the diimine moieties of the neighboring complex cations are antiparallel to each other. All of the complexes were characterized on the basis of the electronic absorption, diffuse reflection, and C-13 NMR spectra., CHEMICAL SOC JAPAN
BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN, 2000年09月, ［査読有り］

Mononuclear copper(II) hydroxo complex: Structural effect of a 3-position of tris(pyrazolyl)borates
K Fujisawa; T Kobayashi; K Fujita; N Kitajima; Y Moro-oka; Y Miyashita; Y Yamada; K Okamoto, New mononuclear nitratocopper(II) complexes ([Cu(NO3){HB(3,5-iPr(2)pz)(3)}] (1)(1) and [Cu(NO3){HB(3-tBu-5-iPrpz)(3)}] (3)) and a novel mononuclear hydroxocopper(II) complex ([Cn(OH){HB(3-tBu-5-iPrpz)(3)}] (4)) have been prepared. These complexes were characterized by X-ray analysis and IR, UV-vis, and EPR spectroscopies. Except for the dinuclear complex ([{Cu[HB(3,5-iPr(2)pz)(3)]}(2)(mu-OH)(2)] (2)), the complexes are mononuclear structures having square-pyramidal (1), trigonal-pyramidal (3), and distorted tetrahedral (4) geometry. In comparison with these structures and their physicochemical properties, the structural effects on the alkyl substitutions at the close 3-position in hydrotris-(pyrazolyl)borates play an important role in modifying the coordination environment about a copper(II) center and their physicochemical properties., CHEMICAL SOC JAPAN
BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN, 2000年08月, ［査読有り］

Optical Active S-Bridged Co^IIIPd^II Polynuclear Complexes Derived from ΔΔ-[Ni{Co(aet)₂(R-pn)₂}]⁴⁺ (aet = 2-Aminoethanethiolate, R-pn = (R)-1,2-Propanediamine)
Yasunori Yamada; Yoko Maeda; Takumi Konno; Kiyoshi Fujisawa; Ken-ichi Okamoto, 光学活性な硫黄架橋3核Ni(II)Co(III)Ni(II)錯体とPd(II)イオンを反応させることにより得られる光学活性な硫黄架橋Co(III)Pd(II)多核錯体の構造を決定するとともに、錯体の分光化学的検討を行った。, CHEMICAL SOC JAPAN
Bull. Chem. Soc. Jpn., 2000年08月, ［査読有り］

Crystal structure and spectrochemical properties of a dinuclear palladium(II) complex with 2,3,5,6-tetra(2-pyridyl)pyrazine
Y Yamada; Y Miyashita; K Fujisawa; K Okamoto, A dinuclear Pd(II) complex bridged with 2,3,5,6-tetra(2-pyridyl)pyrazine (tppz) was newly obtained by the reaction of Pd(II) ion with tppz. The crystal structure of the dinuclear complex was determined by X-ray structural analysis. The spectrochemical properties of the complex are also discussed in relation to the stereochemical behavior., CHEMICAL SOC JAPAN
BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN, 2000年08月, ［査読有り］

Synthesis, Crystal Structure, and Some Spectrochemical Properties of Optically Active S-Bridged Trinuclear Complex ΔΔ-[Ni{Co(aet)₂(R-pn)₂}]⁴⁺ (aet = 2-Aminoethanethiolate, R-pn = (R)-1,2-Propanediamine
Yasunori Yamada; Yoko Maeda; Yoshitaro Miyashita; Kiyoshi Fujisawa; Takumi Konno; Ken-ichi Okamoto, 光学活性なCo(III)を含む錯体配位子とNi(II)錯体を反応させることにより得られる光学活性な硫黄架橋3核錯体の構造を決定するとともに、錯体の分光化学的検討を行った。, CHEMICAL SOC JAPAN
Bull. Chem. Soc. Jpn., 2000年05月, ［査読有り］

"Radical-Controlled" Oxidative Polymerization of m-Cresol Catalyzed by μ-η²:η²-peroxo Dicopper(Ⅱ) Complex
Hideyuki Higashimura; Kiyoshi Fujisawa; Yoshihiko Moro-oka; Masaaki Kubota; Akinobu Shiga; Hiroshi Uyama; Shiro Kobayashi, チロシナーゼモデル錯体を用いてm-クレゾールの酸化重合を行い、高分子材料を得た。得られた高分子材料の分析を行った。, ELSEVIER SCIENCE BV
J. Mol. Catal. A Chem., 2000年04月, ［査読有り］

Synthesis, crystal structures, and some properties of S-bridged Pt(II)-M(III) (M = Co, Rh) dinuclear complexes with square-planar and octahedral geometries
Y Yamada; M Uchida; Y Miyashita; K Fujisawa; T Konno; K Okamoto, A novel dinuclear complex [{Pt(bpy)},{Co(aet)(2)(en)}](3+) (bpy = 2,2'-bipyridine; aet = 2-aminoethanethiolate; en = ethylenediamine) (1) composed of square planar and octahedral geometries was obtained by a substitution reaction of [Ni{Co(aet)(2)(en)}](4+) with [PtCl2(bpy)]. The reactions of fac(S)-[M(aet)(3)] (M = Co-III, Rh-III) with [PtCl2(bpy)] also gave a similar type of S-bridged dinuclear complexes [{Pt(bpy)} {M(aet)(3)}](2+) (M = Co-III (2), Rh-III (3)). The crystal structures of complexes 1, 2, and 3 were determined by X-ray crystallography. All of the Co and Rh atoms in 1, 2, and 3 take approximately octahedral geometry. The Pt atoms in 1, 2, and 3 are coordinated by two N atoms in bpy and two S atoms from C-2-cis(S)-[Co(aet)(2)(en)](+) or [M(aet)(3)] unit, and all of them take square-planar geometry. fac(S)-[Co(aet)(3)] is structurally converted into a mer(S)-[Co(aet)(3)] unit during the course of producing a [{Pt(bpy)},{M(aet)(3)}](2+)-type dinuclear complex, although fac(S)-[Rh(aet)(3)] retains its structure. These complexes were characterized on the basis of the electronic absorption, CD, and C-13 NMR spectra, together with cyclic voltammetry., CHEMICAL SOC JAPAN
BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN, 2000年04月, ［査読有り］

Oxidative polymerization of 2,5-dimethylphenol by tyrosinase-model complex　　　　　　　　　　　　　　　
Shuhei Namekawa; Hideyuki Higashimura; Masaaki Kubota; Akinobu Shiga; Kiyoshi Fujisawa; Yoshihiko Moro-oka; Hiroshi Uyama; Shiro Kobayashi, The oxidative polymerization of 2,5-dimethylphenol (DMP) by tyrosinase model complex gave poly(2,5-dimethyl-1,4-phenylene oxide) (P(2,5-DMPO)) regioselectively and in contrast, that of 2,6-DMP did not afford P(2,6-DMPO) but tetramethyldiphenoquinone (DPQ). P(2,5-DMPO) had heat-reversible crystallinity with a melting point of 300 °C, although P(2,6-DMPO) did not show crystalline once melted. It shows that the thermoplastic moldings of (2,5-DMPO) can posses high heat-resistance nearly up to the melting point, indicating a strong candidate of P(2,5-DMPO) as a new super engineering plastics. The reaction of the dimer by the enzyme model complex showed that the chain extension mechanism of the polymerization of 2,5-DMP differed from that of 2,6-DMP., ACS
American Chemical Society, Polymer Preprints, Division of Polymer Chemistry, 2000年03月

'Radical-controlled' oxidative polymerization of o-cresol catalyzed by mu-(2)(eta):(2)(eta)-peroxo dicopper(II) complex
H Higashimura; K Fujisawa; Y Moro-oka; M Kubota; A Shiga; H Uyama; S Kobayashi, Described is an oxidative polymerization of o-cresol catalyzed by (1,4,7-triisopropyl-1,4,7-triazacyclononane)copper complex, from which a mu-eta(2) : eta(2): eta(2)-peroxo dicopper(II) complex is formed under dioxygen. This complex reacts with o-cresol to give 'controlled' phenoxy radical-copper(I) complex exclusively without formation of 'free' phenoxy radicals. The resulting polymer was composed mainly of 2-methyl-1,4-phenylene oxide unit and showed high thermal stability. The polymerization catalyzed by (N,N,N',N'-tetramethylethylenediamine)copper complex,a typical-catalyst for 2,6-dimethylphenol polymerization, gave the polymer containing larger amounts of o-linkage structures and quinone moieties, (C) 2000 Elsevier Science B,V. All rights reserved., ELSEVIER SCIENCE BV
APPLIED CATALYSIS A-GENERAL, 2000年03月, ［査読有り］

“Radical-Controlled” Oxidative Polymerization of 4-Phenoxyphenol by a Tyrosinase Model Complex Catalyst to Poly(1,4-phenylene oxide).
Hideyuki Higashimura; Masaaki Kubota; Akinobu Shiga; Kiyoshi Fujisawa; Yoshihiko Moro-oka; Hiroshi Uyama; Shiro Kobayashi, チロシナーゼモデル錯体を用いて4-フェノキシフェノールの酸化重合を行い、熱硬化性の優れた高分子材料を得た。配位子のかさ高い置換基によりフェノールのオルト位での反応を完全に制御できた。本論文では、反応機構について詳細に検討した。, AMER CHEMICAL SOC
Macromolecules, 2000年03月, ［査読有り］

New crystalline polymers: Poly(2,5-dialkyl-1,4-phenylene oxide)s
Higashimura, H.; Fujisawa, K.; Mom-oka, Y.; Namekawa, S.; Kubota, M.; Shiga, A.; Uyama, H.; Kobayashi, S., チロシナーゼモデル錯体を用いて、2,5-ジメチルフェノールの重合を行った。得られた高分子材料は、303度に結晶融点を持つ熱可逆性高分子であった。十分実用に耐えられると考えられる。なお、本論文はこの号の表紙を飾った。
Macromolecular Rapid Communications, 2000年, ［査読有り］

Stereochemistry and electrochemical properties of molybdenum ions incorporated into S-bridged polynuclear structures
Yoshitaro Miyashita; Yasunori Yamada; Kiyoshi Fujisawa; Takumi Konno; Kan Kanamori; Ken-Ichi Okamoto, The reactions of/ac(5)-[M(aet)j] (M = Ir1" or Rh"1
aet = 2-aminoethanethiolate) with [NH4]2[MoCl5(H2O)] in both anaerobic and aerobic atmospheres gave linear-type S-bridged trinuclcar complexes, [MoIV{Ir(aet)3}2]4t 1 and [Mom{Rh(aet)3}2]3'f' 1. Complex 2 was spontaneously oxidized by exposure to air and converted into a novel S-bridged pentanuclear complex, [Mov2O2(u-O){Rh(aet)3}3]43, and the structural change from 2 to 3 was monitored by UV-vis spectroscopy. The crystal structures of lBr4-4H2O, 2Br3-H2O, and 3Br4-6H2O were determined by X-ray diffraction. In the complex cations 1 and 2, Mo4t and Mo3t ions are co-ordinated by the six thiolato sulfur atoms from two./tfc(S)-[M(aet)3] units and relatively short metal-metal distances (2.7469(7) and 2.860(3) A) are observed, respectively. In 3 the Mo-O-Mo angle (157.0(4)°) in the Mo2O2(u-O)4+ core is unique and the core is co-ordinated by the eight thiolato sulfur atoms of three/ac(5)-[Rh(aet)3] units. The cyclic voltammograms for 1 and 2 indicate that the oxidation states of the molybdenum ions, which are incorporated into the S-bridged polynuclear structures, and stability of the complexes, depend upon the metal ions in the terminal building blocks,y?/c-(S')-[M(aet)3]. The absorption spectrum of each complex exhibited characteristic intense bands in the visible region, which relate to the molybdenum ions. © The Royal Society of Chemistry 2000.
Journal of the Chemical Society, Dalton Transactions, 2000年, ［査読有り］

"Radical-Controlled" Oxidative Polymerization of 4-Phenoxyphenol to Poly(1,4-phenylene oxide) by μ-η²:η²-peroxo Dicopper(Ⅱ) Complex　　　　　　　　　　　　　　　
Hideyuki Higashimura; Kiyoshi Fujisawa; Yoshihiko Moro-oka; Masaaki Kubota; Akinobu Shiga; Hiroshi Uyama; Shiro Kobayashi, チロシナーゼモデル錯体を用いてo-クレゾールの酸化重合を行い、高分子材料を得た。得られた高分子材料の分析を行った。
Appl. Catal., A, 2000年, ［査読有り］

Coupling selectivity in the radical-controlled oxidative polymerization of 4-phenoxyphenol catalyzed by (1,4,7-triisopropyl-1,4,7-triazacyclononane)copper(ll) complex
H Higashimura; K Fujisawa; S Namekawa; M Kubota; A Shiga; Y Moro-Oka; H Uyama; S Kobayashi, Various effects on the coupling selectivity of the oxidative polymerization of 4-phenoxyphenol catalyzed by (1,4,7-triisopropyl-1,4,7-triazacyclononane)copper(II) halogeno complex [Cu(tacn)X-2] are described. With respect to the amount of the catalyst and the nature of the halide ion (X) of Cu(tacn)X-2, the coupling selectivity hardly changed. The Cu(tacn) catalyst possessed a turnover number greater than 1860. As the temperature of the reaction and the polarity of the reaction solvent were elevated, the C-O coupling at the o-position increased, but the C-C coupling was not involved. For the polymerization in toluene at 80 degreesC, poly(1,4-phenylene oxide), obtained as a methanol-insoluble part, showed the highest number-average molecular weight of 4000 with a melting point (T-m) of 195 degreesC. Only a slight change in the coupling selectivity was observed in the presence or absence of hindered amines as the base. Surprisingly, however, the C-O selectivity decreased from 100 to 24% with less hindered amines, indicating that the selectivity drastically changed from a preference for C-O coupling to a preference for G-C coupling. (C) 2000 John Wiley & Sons, Inc., JOHN WILEY & SONS INC
JOURNAL OF POLYMER SCIENCE PART A-POLYMER CHEMISTRY, 2000年, ［査読有り］

Stereochemistry and electrochemical properties of molybdenum ions incorporated into S-bridged polynuclear structures
Y Miyashita; Y Yamada; K Fujisawa; T Konno; K Kanamori; K Okamoto, The reactions of fac(S)-[M(aet)(3)] (M = Ir-III or Rh-III; aet = 2-aminoethanethiolate) with [NH4](2)[MoCl5(H2O)] in both anaerobic and aerobic atmospheres gave linear-type S-bridged trinuclear complexes, [Mo-IV {Ir(aet)(3)}(2)](4+) 1 and [Mo-III{Rh(aet)(3)}(2)](3+) 2. Complex 2 was spontaneously oxidized by exposure to air and converted into a novel S-bridged pentanuclear complex, [ (Mo2O2)-O-V(mu-O){Rh(aet)(3)}(3)](4+) 3, and the structural change from 2 to 3 was monitored by UV-vis spectroscopy. The crystal structures of 1Br(4). 4H(2)O, 2Br(3). H2O, and 3Br(4). 6H(2)O were determined by X-ray diffraction. In the complex cations 1 and 2, Mo4+ and Mo3+ ions are co-ordinated by the six thiolato sulfur atoms from two fac( S)-[M(aet)(3)] units and relatively short metal-metal distances (2.7469(7) and 2.860(3) Angstrom) are observed, respectively. In 3 the Mo-O-Mo angle (157.0(4)degrees) in the Mo2O2(mu-O)(4+) core is unique and the core is co-ordinated by the eight thiolato sulfur atoms of three fac( S)-[Rh(aet)(3)] units. The cyclic voltammograms for 1 and 2 indicate that the oxidation states of the molybdenum ions, which are incorporated into the S-bridged polynuclear structures, and stability of the complexes, depend upon the metal ions in the terminal building blocks, fac(S)-[M(aet)(3)]. The absorption spectrum of each complex exhibited characteristic intense bands in the visible region, which relate to the molybdenum ions., ROYAL SOC CHEMISTRY
JOURNAL OF THE CHEMICAL SOCIETY-DALTON TRANSACTIONS, 2000年, ［査読有り］

Synthesis, Structure and Reactivity of Phenoxo Copper(Ⅱ)Complexes, Cu(OAr)(HB(3,5-Prⁱ₂pz)₃)(Ar=C₆H₄-p-F, 2,6-Me₂C₆H₃, 2,6-Bu^t₂C₆H
Kiyoshi Fujisawa; Yusaku Iwata; Nobumasa Kitajima; Hideyuki Higashimura; Masaaki Kubota; Yoshitaro Miyashita; Yasunori Yamada; Ken-ichi Okamoto; Yoshihiko Moro-oka, チロシナーゼの反応中間体と考えられる単核フェノキソ銅(II)錯体を合成し、そのうち一つの構造を決定した。アルゴン下、酸素下で自己分解反応を行い、酸化生成物の解析を行い、チロシナーゼの反応機構にも討論した。, CHEMICAL SOC JAPAN
Chem. Lett., 1999年08月, ［査読有り］

Electrochemical and spectroelectrochemical studies on sandwich-type bis(phthalocyaninato)lanthanide complexes
C Harnoode; K Takamura; H Kubota; K Sho; K Fujisawa; F Kitamura; T Ohsaka; K Tokuda, Sandwich-type bis(phthalocyaninato)lanthanide complexes, [Ln(Pc)(2)](z), exhibit intriguing characteristics which stem from the interactions between the two pi-conjugated phthalocyanine rings held by the central metal ion in close proximity, and they have been explored as materials for electrochromic displays, molecular semiconductors, gas-sensors and for nonlinear optical applications. This article reviews some topics on their structural, electrochemical, chemical, and spectral characteristics., ELECTROCHEMICAL SOC JAPAN
ELECTROCHEMISTRY, 1999年08月, ［査読有り］

Novel highly-regioselective oxidative-polymerization of 4-phenoxyphenol to poly(1,4-phenylene oxide) catalyzed by tyrosinase model complexes
H Higashimura; K Fujisawa; Y Moro-oka; M Kubota; A Shiga; H Uyama; S Kobayashi, A highly regioselective oxidative coupling of 4-phenoxyphenol (PPL) catalyzed by tyrosinase model complexes, (hydrotris(3,5-diphenyl-1-pyrazolyl)borate) copper(II) chloride (Cu(tpzb)Cl) and (1,4,7-triisopropyl-1,4,7-triazacyclononane) copper(II) dichloride (Cu(tacn)Cl-2), is described. The polymerization of PPL oxidized by an equimolar of 2,2'-azobisisobutyronitrile in toluene, regarded as a model system of free phenoxy radical coupling, gave C-C coupling dimers besides C-O coupling dimers at the initial polymerization stage and yielded the polymer having no melting point. However, the polymerization of PPL catalyzed by Cu(tpzb)Cl and Cu(tacn)Cl-2 under dioxygen in toluene gave no C-C coupling dimers, and hence, yielded poly(1,4-phenylene oxide) showing crystallinity with melting points., ELSEVIER SCIENCE PUBL B V
SCIENCE AND TECHNOLOGY IN CATALYSIS 1998, 1999年, ［査読有り］

Highly regioselective oxidative polymerization of 4-phenoxyphenol to poly(1,4-phenylene oxide) catalyzed by tyrosinase model complexes　　　　　　　　　　　　　　　
Hideyuki Higashimura; Kiyoshi Fujisawa; Yoshihiko Moro-oka; Masaaki Kubota; Akinobu Shiga; Hiroshi Uyama; Shiro Kobayashi, Crystalline poly(1,4-phenylene oxide) (PPO) was successfully synthesized showing a melting point by highly regioselective oxidative polymerization of 4-phenoxyphenol using tyrosinase model complex catalysts. μ-η2:η2-peroxo dicopper (II) complexes were formed in situ as the active dioxygen intermediates., ACS
American Chemical Society, Polymer Preprints, Division of Polymer Chemistry, 1998年08月

Highly regioselective oxidative polymerization of 4-phenoxyphenol to poly(1,4-phenylene oxide) catalyzed by tyrosinase model complexes
H Higashimura; K Fujisawa; Y Moro-oka; M Kubota; A Shiga; A Terahara; H Uyama; S Kobayashi, AMER CHEMICAL SOC
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 1998年08月, ［査読有り］

Highly regioselective oxidative polymerization of 4-phenoxyphenol to poly(1,4-phenylene oxide) catalyzed by tyrosinase model complexes.
H Higashimura; K Fujisawa; Y Moro-oka; M Kubota; A Shiga; H Uyama; S Kobayashi, チロシナーゼモデル錯体を用いて4-フェノキシフェノールの酸化重合を行い、熱硬化性の優れた高分子材料を得た。配位子のかさ高い置換基によりフェノールのオルト位での反応を完全に制御できた。, AMER CHEMICAL SOC
ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY, 1998年08月, ［査読有り］

Cu-63 NMR study of copper(I) carbonyl complexes with various hydrotris(pyrazolyl)borates: Correlation between Cu-63 chemical shifts and CO stretching vibrations
S Imai; K Fujisawa; T Kobayashi; N Shirasawa; H Fujii; T Yoshimura; N Kitajima; Y Moro-oka, Copper(I) carbonyl complexes with a series of hindered L-R1,L-R2 ligands (L: hydrotris(pyrazolyl)borate, R1 and R2 are substituents at the 3- and 5-positions of the pyrazole ring, respectively), (LCuCO)-Cu-R1,R2 [R1, R2 = Me, Me (1), i-Pr, i-Pr (2), t-Bu, Me (3), t-Bu, i-Pr (4), Ph, i-Pr (5), Ph, Ph (6)1 have been synthesized and characterized by]H NMR and IR spectroscopy and elemental analysis. The molecular structures of 3 and 6 have been determined by X-ray crystallography. The electronic structures of copper(I) sites are characterized by means of Cu-63 NMR spectroscopy and by the C=O stretching vibration. The sharp Cu-63 NMR signals are observed for (LCuCO)-Cu-R1,R2 complexes in toluene at room temperature. The Cu-63 NMR Signals of copper(I) complexes with alkyl-substituted ligands (1-4) are observed in lower field than those of the phenyl derivatives (5, 6) correlating with the electron-density at the copper center. This argument is supported by the good correlation between the delta((CU)-C-63) value and C=O stretching vibration which is a sensitive indicator of the extent of back-donation of the Cu d electrons to the antibonding C=O orbitals., AMER CHEMICAL SOC
INORGANIC CHEMISTRY, 1998年06月, ［査読有り］

A Superoxodicopper(Ⅱ) Complex Oxidatively Generated by a Reaction of Di-μ-hyrdodicopper(Ⅱ) Complex with Hydrogen Peroxide
Masahito Kodera; Yoshimitsu Tachi; Shun Hirota; Kou Katayama; Hisashi Shimakoshi; Koji Kano; Kiyoshi Fujisawa; Yoshihiko Moro-oka; Yoshinori Naruta; Teizo Kitagawa, 架橋ヒドロキソ架橋スーパーオキソ銅(II)錯体を合成し、各種分光手段によりこの構造であることを討論した。, CHEMICAL SOC JAPAN
Chem. Lett., 1998年05月, ［査読有り］

Preparation, spectroscopic, characterization, and molecular structure of copper(I) aliphatic thiolate complexes
K Fujisawa; S Imai; N Kitajima; Y Moro-oka, 銅の代謝や運搬に関与するタンパク質のモデル錯体をかさ高いアルキルチオールを用いて合成し、構造を決定した。各種分光的性質の検討を行った。, AMER CHEMICAL SOC
INORGANIC CHEMISTRY, 1998年01月, ［査読有り］

Two-coordinate gold(I) aliphatic thiolate complex: The Au-S distance is smaller than the Ag-S one
K Fujisawa; S Imai; Y Moro-oka, We prepared the first example of two-coordinate aliphatic monothiolate gold(I) complex. Its structural parameter was compared with that of copper(I) and silver(I) derivatives. The physical properties may be used to differentiate the coordination mode of gold(I) complexes., CHEMICAL SOC JAPAN
CHEMISTRY LETTERS, 1998年, ［査読有り］

Square planar nickel compounds with bulky thiols
T Yamamura; H Watanabe; Y Niino; K Fujisawa; Y Morooka, Details of the syntheses and the results of X-ray structural analyses of square planar Ni compounds with aliphatic thiolato-sulfur ligands, [Ni(dpmep)(2)] (1) and [Ni(tpttd)] (2), where Hdmep and H(2)tpttd are the abbreviations for 2-(2,2-diphenyl-2-mercaptoethyl)pyridine and 2,2',11,11'-tetraphenyl-1,5,8,12-tetrathiadodecane respectively, are presented. Each of the thiolato-sulfur atoms of these compounds is sterically protected by two benzene rings at the alpha carbon position to suppress dimerization upon synthesis. 1.1.5Ch(2)Cl(2) . MeCN crystallizes monoclinic P2(1)/n with a = 18.362(3), b = 16.894(4), c = 13.273(4) Angstrom, beta = 104.59(2)degrees, V = 3984(3) Angstrom(3) and Z = 4.2.1.5MeCN crystallizes triclinic <P(1)over bar> with a = 15.091(6), b = 15.661(3), c = 14.085(7) Angstrom, alpha = 96.00(2), beta = 90.89(4), gamma = 99.70(2)degrees, V = 32.61(4) Angstrom(3) and Z = 4. The Ni-S and Ni-N bond lengths of 1 were compared with those of the nickel center in the A-cluster of carbon monoxide dehydrogenase. (C) 1997 Elsevier Science S.A., ELSEVIER SCIENCE SA LAUSANNE
INORGANICA CHIMICA ACTA, 1997年10月, ［査読有り］

Synthesis and characterization of the benzoylformato ferrous complexes with the hindered tris(pyrazolyl)borate ligand as a structural model for mononuclear non-heme iron enzymes
S Hikichi; T Ogihara; K Fujisawa; N Kitajima; M Akita; Y Morooka, By using a hindered tripodal ligand, hydrotris(3-tert-butyl-5-isopropylpyrazo-1-y)borate HB(3-tBu-5-iPrpz)(3), a series of monomeric ferrous complexes having acetate, hydroxide, and benzoylformate ligands were synthesized. Reaction of KHB(3-tBu-5-iPrpz)(3) with anhydrous Fe(OAc)(2) yielded acetato complexes Fe(OAc)[HB(3-tBu-5-iPrpz)(3)] (1) and Fe(OAc)[HB(3-tBu-5-iPrpz)(3)](3-iPr-5-tBup (2). A hydroxo complex Fe(OH)[HB(3-tBu-5-iPrpz)(3)] (3) was prepared by the treatment of 1 or 2 with aqueous NaOH. The geometry of Fe(II) in 3 is a slightly distorted tetrahedron as determined by X-ray crystallography. The hydroxo complex 3 reacted with benzoylformic acid to give the benzoylformato complex Fe(O2CC(O)Ph)[HB(3-tBu-5-iPrpz)(3)] (4), which showed thermochromism which depended on the coordination geometry of the benzoylformate ligand. The Fe(LT) ion in the colorless form of 4 isolated at 4 degrees C is coordinated by a tetrahedral N3O1 ligand donor set including the unidentate benzoylformato ligand. On the other hand, the bluish purple form of 4 isolated ar -20 degrees C has a five-coordinate trigonal bipyramidal Fe(IT) center. The benzoylformate ligand in this bluish purple form works as a chelate ligand through coordination of the unidentate carboxylate oxygen atom as well as the ketonic oxygen atom. A benzoylformato complex containing an additional pyrazole, Fe(O2CC(O)Ph)[HB(3-tBu-5-iPrpz)(3)](3-iPr-5-tBupzH) (5), was obtained by the reaction of 3 with benzoylformic acid in the presence of 3-tert-butyl-5-isopropylpyrazole. The iron atom in 5 is coordinated by an N4O1 ligand donor set with trigonal bipyramidal geometry. A hydrogen-bonding interaction between the carboxylate oxygen atom and the additional pyrazole's NH proton in 5 is suggested from the short distance between O-carboxylate and N-pyrazole observed in the X-ray structure and the absence of the nu NH vibration in the LR spectrum., AMER CHEMICAL SOC
INORGANIC CHEMISTRY, 1997年09月, ［査読有り］

Dimanganese Complexes Bridged with a (μ-X)(μ-Carboxylato)Unit as Models for the Active Site of Manganese Catalase(X=OH, O or (O)₂)
Masahisa Osawa; Kiyoshi Fujisawa; Nobumasa Kitajima; Yoshihiko Moro-oka, 新規架橋ヒドロキソ架橋カルボキシラトマンガン錯体の合成、構造決定を行った。マンガン含有カタラーゼの構造に関する討論を行った。, CHEMICAL SOC JAPAN
Chem. Lett., 1997年, ［査読有り］

A monomeric zinc complex ligated by an unsymmetric hydrotris(pyrazolyl)borate containing an OH group
M Osawa; M Tanaka; K Fujisawa; N Kitajima; Y Morooka, A novel zinc complex having an unsymmetric tris(pyrazolyl)borate, Zn(OAc)[HB(3-Me(2)C(OH)-5-iPrpz)(3,5-iPr(2)pz)(2)], was synthesized by the transmetalation of an oxygenated product formed a dimanganese(II, II) complex {[Mn[HB (3,5-iPr(2)pz)(3)]}(2)(OH)(2) with molecular oxygen., CHEMICAL SOC JAPAN
CHEMISTRY LETTERS, 1996年, ［査読有り］

A MONOMERIC SIDE-ON SUPEROXOCOPPER(II) COMPLEX - CU(O-2)(HB(3-TBU-5-IPRPZ)(3))
K FUJISAWA; M TANAKA; Y MOROOKA; N KITAJIMA, 単核スーパーオキソ銅(II)錯体の構造を初めて決定した。かさ高い置換基を使うと酸素は一電子還元で止まり、スーパーオキソ錯体が生成した。, AMER CHEMICAL SOC
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 1994年12月, ［査読有り］

Synthesis, Structure and Magnetic Properties of a Linear Trimanganese (III, II, III) Complex Bridged with a (μ-Hydroxo) bis(acetato)Unit
Nobumasa Kitajima; Masahisa Osawa; Sadako Imai; Kiyoshi Fujisawa; Yoshihiko Moro-oka; Kristel Heerwegh; Christopher A. Reed; Peter D. W. Boyd, 架橋ヒドロキソ架橋アセトナマンガン錯体の合成、構造決定を行い、磁気的性質を明らかにした。, AMER CHEMICAL SOC
Inorg. Chem., 1994年10月, ［査読有り］

Formation of a μ-η²:η²-Disulfide Dinuclear Copper (II) Complex by Thermal Decomposition of a Thiolate Complex via C-S Bond Cleavage
Kiyoshi Fujisawa; Yoshihiko Moro-oka; Nobumasa Kitajima, トリフェニルメタンチオラート銅(II)錯体を室温で放置するとC-S結合が等価に開裂し、ジスルフィド錯体が生成することを示すとともに、その構造を初めて決定した。その性質についても明らかにした。, ROYAL SOC CHEMISTRY
J. Chem. Soc., Chem. Commun. 1994(5), 623-624., 1994年03月, ［査読有り］

SYNTHESIS, MOLECULAR-STRUCTURE, AND REACTIVITY OF (ALKYLPEROXO)COPPER(II) COMPLEX
N KITAJIMA; T KATAYAMA; K FUJISAWA; Y IWATA; Y MOROOKA, アルキルパーオキソ銅(II)錯体の構造を初めて決定し、その反応性に関する検討を行った。酸素-酸素あるいは酸素-銅間の結合が等価に開裂することを明らかにした。, AMER CHEMICAL SOC
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 1993年08月, ［査読有り］

Formation of (μ-Hyroxo)(μ-Azido) Dinuclear Copper Complex from μ-η²:η²-Peroxo Complex
Nobumasa Kitajima; Kiyoshi Fujisawa; Shiro Hikichi; Yoshihiko Moro-oka, 我々が合成・構造決定したパーオキソ銅(II)錯体とアジド化物イオンとの反応から表記の錯体が得られ、構造決定した。タンパク質に関する検討も併せて行った。, AMER CHEMICAL SOC
J. Am. Chem. Soc., 1993年08月, ［査読有り］

SPECTROSCOPIC STUDIES OF SIDE-ON PEROXIDE-BRIDGED BINUCLEAR COPPER(II) MODEL COMPLEXES OF RELEVANCE TO OXYHEMOCYANIN AND OXYTYROSINASE
MJ BALDWIN; DE ROOT; JE PATE; K FUJISAWA; N KITAJIMA; EI SOLOMON, Spectrosopic studies on two side-on mu-eta2:eta2 peroxide-bridged cupric dimers, [Cu(HB(3,5-R2pz)3)]2(O2), where (HB(3,5-R2pz)3) is a tris(pyrazolyl)borate ligand and R = i-Pr or Ph, are presented and compared to our previous studies of end-on bound(eta1) peroxide-coppper monomer and bridged dimer (trans-mu-1,2) complexes. Two transitions at 350 nm (epsilon = 26 000 M-1 cm-1) and 538 nm (epsilon = 2000 M-1 cm-1) are assigned as peroxide-to-copper charge-transfer transitions. A method has been developed to quantitate electron density donation from the ligand to the metal center using the intensity of the ligand-to-metal charge-transfer transitions. It is found that the side-on bridging peroxide donates significantly more electron density from the peroxide pi* orbitals to the coppers than does,peroxide in end-on bound monomer and dimer complexes. The amount of charge donation is proportional to the number of sigma bonds between the peroxide and the coppers (side-on bridged dimer = 4, end-on bridged dimer = 2, end-on monomer = 1). The increased charge donation results in a less negative peroxide in the side-on complex and should in principle produce a stronger O-O bond. Four vibrational modes are assigned in the resonance Raman and infrared spectra on the basis of isotopic shifts at 763 (rR, 723 cm-1 with O-18(2)), 331 (IR, 321 cm-1 with O-18(2)), 284 (rR, no shift with O-18(2)), and 572 cm-1 (based on an overtone at 1144 cm-1 in rR, 1098 cm-1 with O-18(2)) in the R = Ph complex, with corresponding peaks at 749, 285, and 1055 cm-1 in the resonance Raman spectra of the R = i-Pr complex. A normal coordinate analysis shows that the oxygen-oxygen force constant, k(O-O), is smaller in the side-on bridged complex (2.4 mdyn/angstrom) than in the end-on monomer (2.9 mdyn/angstrom) or end-on bridged dimer (3.1 mdyn/angstrom), and thus the O-O bond is weaker in the side-on complex than in the end-on, despite its greater peroxide charge donation. This is direct evidence for the pi acceptor ability of the peroxide in this side-on bridged structure, which involves some peroxide sigma* character mixing into the highest energy occupied molecular orbital, as predicted by Xalpha calculations [Ross, P. K.; Solomon, E. I. J. Am. Chem. Soc. 1991, 113, 3246-3259]. Using the correlation of charge-transfer intensities to ligand charge donation, the charge-transfer intensity of oxyhemocyanin indicates that it likely has four copper-peroxide bonds and thus a side-on peroxide bridging structure. The electronic structure of this side-on bridging geometry in oxyhemocyanin explains its unique spectroscopic features, including the high intensity and energy of the 345-nm absorption band, the low O-O stretching frequency, and the lack of a symmetric Cu-O stretch in the expected energy range of the resonance Raman spectrum. This electronic structure also provides insight into the mechanisms of oxygen binding and activation in hemocyanin and tyrosine., AMER CHEMICAL SOC
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 1992年12月

X-RAY STRUCTURE OF THIOLATOCOPPER(II) COMPLEXES BEARING CLOSE SPECTROSCOPIC SIMILARITIES TO BLUE COPPER PROTEINS
N KITAJIMA; K FUJISAWA; M TANAKA; Y MOROOKA, ブルー銅タンパク質の性質を再現できるチオラート銅(II)錯体の構造を初めて決定した。この特異な性質再現には、N3S型配位子対が平面内で強く結合することが重要であることを示した。, AMER CHEMICAL SOC
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 1992年11月