1990 Fiscal Year Final Research Report Summary
Spin Exchange Interaction and Electron-Density Distribution in Dimeric Copper (II) Carboxylates
| Project/Area Number |
62580042
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
結晶学
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| Research Institution | Faculty of Science and Technology, Keio University |
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Principal Investigator |
OHBA Shigeru Faculty of Science and Technology, Assistant Professor, 理工学部, 専任講師 (50146578)
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| Co-Investigator(Kenkyū-buntansha) |
SAITO Yoshihiko Faculty of Science and Technology, Guest Professor, 理工学部, 客員教授
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| Project Period (FY) |
1987 – 1989
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| Keywords | Spin Exchange Interaction / Dimeric Copper Carboxylate / Accurate X-Ray Crystal Structure Analysis |
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| Research Abstract |
Structural comparison between copper formates and acetates has been made for pyridine, urea, and alpha-, beta- and gamma picoline adducts to confirm that there is no remarkable difference in dimensions of their central Cu_2(OCO)_4 cage. Molecular orbital calculation for bridging ligands suggested that the larger is the number of electrons in the OCO path, the stronger is the antiferromagnetic spin super-exchange interaction in the binuclear copper complex. However, the very large -2J values of triorgano-silane carboxylate and -germane carboxylate, ca 1000 cm^<-1>, might involve other primary factors. Structures of dimeric copper trichloroacetates having relatively small -2J value, ca 100 cm^<-1>, have been determined in order to confirm that the coordination geometry around the Cu atom is deformed from square pyramidal to trigonal bipyramidal. A magneto-structural correlation was found clearly that the -2J value decreases linearly with the Cu...Cu distance, or with the average deviation of the Cu-O-C bond angles from 123^ﾟ. The reason why the spin-exchange interactions become weak in the trigonal bipyramidal coordination geometry may be as follows : The spin density of Cu^<2+> is asummed to be localized in the d _z2 orbital, the axial direction of which is perpendicular to each other fot two Cu atoms, and the bridging ligand cannot transmit the spin density effectively.
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Research Products
(10 results)
