1997 Fiscal Year Final Research Report Summary
Construction of Reaction Center by Reductive Cleavage of Metal-Metal Bonds
| Project/Area Number |
08454232
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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 |
物質変換
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| Research Institution | Institute for Molecular Science |
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Principal Investigator |
TANAKA Koji Institute for Molecular Science, Professor, 分子科学研究所, 教授 (00029274)
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| Project Period (FY) |
1996 – 1997
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| Keywords | Carbon Dioxide Reduction / Metal-Sulfur Cluster / Metal-Metal Bond Cleavage / Oxalate Formation |
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| Research Abstract |
Electrochemical reduction of CO_2 catalyzed by [(MC_p^<**>) _3 (mu3-S)_2] (BPh_4)_2 (M=Co, Rh) selectively produced C_2O_4^<2-> as the first example of oxalate formation in homogeneous syatem and the original trinuclear clusters are recovered intact after the electrolysis. Similar electrochemical reduction of CO_2 in the presence of [(IrC_p^<**>)_3 (mu3-S)_2] (BPh_4)_2 ([Ir_3S_2] (BPh_4)_2) in CH_3CN at -1.30V (vs.Ag/AgCl) also produced C_2O_4^<2-> with a current efficiency of 60%, but [(IrC_p^<**>)_2 (Ir-eta^<4->Cp^<**>CH_2CN) (mu3-S)_2]^+ ([Ir_3S_2CH_2CN]^+) was isolated from the electrolyte solution. The crystal structure of [Ir_3S_2CH_2CN] (BPh_4) by X-ray analysis revealed that a linear CH_2CN group is linked at the exo-position of a Cp^<**> ligand, and the Cp^<**>CH_2CN group coordinates to an Ir atom with an eta^<4->mode. The cyclic voltammongram of [Ir_3S_2CH_2CN]^+ in CH_3CN under CO_2 exhibited a strong catalytic current due to the reduction of CO_2, while that of [Ir_3S_2]^<2+> did not show an interaction with CO_2 in the same solvent. Thus, the reduced form of [Ir_3S_2CH_2CN]^+ works as the active species in the reduction of CO_2. The IR spectra of [Ir_3S_2CH_2CN]^+ in CD_3CN showed a reversible adduct formation with CO_2. The controlled potential electrolysis of [Ir_3S_2CH_2CN]^+ at -1.50V under CO_2 evidenced the generation of C_2O_4^<2-> through a 1 : 2 adduct between [Ir_3S_2CH_2CN]^0 and CO_2. A coupling reaction of two CO_2 molecules activated on adjacent mu3-S and Ir in Ir_3S_2CH_2CN]^0 is proposed for the first selective generation of C_2O_4^<2->.
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[Publications] T.OOKUBO,H.SUGIMOTO,T.NAGAYAMA,H.MASUDA,T.SATO,K.TANAKA,Y.MAEDA,H.OKAWA,Y.HAYASHI,A.UEHARA,and M.SUZUKI: ""cis-m-1,2-Peroxo Diiron Complex : structure and Reversible Oxygenation"" J.Am.Chem.Soc.118. 701 (1996)
Description
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