2005 Fiscal Year Final Research Report Summary
Second Generation Octahedral Coordination Chemistry based on Hexametal Cluster Units
| Project/Area Number |
15350029
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Inorganic chemistry
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| Research Institution | Hokkaido University |
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Principal Investigator |
SASAKI Yoichi Hokkaido Univ., Graduate School of Science, professor, 大学院・理学研究科, 教授 (30004500)
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| Co-Investigator(Kenkyū-buntansha) |
ABE Masaaki Hokkaido Univ., Graduate School of Science, Research Associate, 大学院・理学研究科, 助手 (90260033)
TSUGE Kiyoshi Hokkaido Univ., Graduate School of Science, Research Associate, 大学院・理学研究科, 助手 (60280583)
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| Project Period (FY) |
2003 – 2005
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| Keywords | Metal Cluster Complexes / Hexanuclear Metal Complexes / Rhenium Complexes / Emissive Complexes / Ligand Substitution Reactions / Self-assembled Monolayers / Redox Reactions / Ligand-Ligand Interactions |
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| Research Abstract |
Octahedal hexametal clusters are known for various transition metal ions. Among them, those with d^4 metal ions such as Re(III), Mo(II) and W(II) are particularly stable with twelve electron-precise metal-metal single bonds. In this project, d^4 octahedral hexanuclear cluster complexes are considered as a target of a second generation of octahedral metal coordination chemistry. The purpose of this study is to clarify the similarity and difference between the octahedral cluster complexes and simple mononuclear octahedral complexes. The results are summarized as follows. (i) Ligand substitution properties. Kinetic study of the ligand substitution reactions at the terminal sites of the hexarhenium(III) clusters revealed that pyridine ligand is more rapidly substituted than chloride. This is in reverse trend from that of mononuclear complexes where less basic chloride ligand is replaced more easily. (ii) Redox reactions. Hexarhenium(III) complexes undergo one-electron oxidation. The redox
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potential shifts to positive direction as the number of terminal pyridine ligands increases in the mixed terminal pyridine-chloride system. This is in reverse direction from the expectation by considering the ligand basicity. The two facts, (i) and (ii), manifest unique characteristics of the hexametal clusters ; good π accepting and poor π donoating properties as opposed to typical low-spin d^6 mononuclear metal centers. (iii) Emissions. The d^4 octahedral clusters exhibit strong red emissions. Detailed temperature dependence of the emissions revealed curious behavior of emission life-times and emission energies. These results were successfully analyzed by considering four excited state sublevels. (iv) Self-assembled monolayers. Hexarhenium clusters were successfully fixed onto the gold electrode surfaces by using strong Au-S bond. The S-site was introduced to the ligand pyridine derivatives attached to the hexanuclear unit. Also the hexarhenium cluster unit was chemically combined to oxo-centered triruthenium unit both in solution and on the gold surface. The surface electrochemistry of the hexarhenium clusters and triruthenium-hexarhenium hybrid complexes have been studied. These results (i) - (iv) revealed important differences and similarities of the octahedral hexametal cluster complexes and simple mononuclear metal centers. Less
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Research Products
(58 results)
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[Journal Article] A Pair of Seven Coordinate Oxorhenium Complexes, [Re^<IV>(O)(tpen)]^<2+> and [Re^v(O)(tpen)]^<3+> (tpen = N,N,N',N'-Tetrakis(2-pyridylmethyl) ethylenediamine).2004
Author(s)
H.-Y.Jin, S.Ikari, K.Kobayashi, K.Umakoshi, H.Sugimoto, A.Mitani, M.Abe, Y.Sasaki, T.Ito
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Journal Title
Bull.Chem.Soc.Jpn. 77(6)
Pages: 1139-1146
Description
「研究成果報告書概要(欧文)」より
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[Journal Article] Preparation, Structures, and Redox and Emission Characteristics of the Isothiocyanate Complexes of Hexarhenium(III) Clusters, [Re_6(μ_3-E)_8(NCS)_6]^<4-> (E = S, Se).2003
Author(s)
T.Yoshimura, Z.-N.Chen, A.Itasaka, M.Abe, Y Sasaki, S.Ishizaka, N.Kitamura, S.S.Yarovoi, S.F Solodovnikov, V.E.Fedorov
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Journal Title
Inorg.Chem. 42(10)
Pages: 4857-4863
Description
「研究成果報告書概要(欧文)」より
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[Book] 新 水の分析2005
Author(s)
佐々木陽一(分担執筆)
Total Pages
472(11)
Publisher
化学同人
Description
「研究成果報告書概要(和文)」より
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