| | 1 | Author
| AndreasF. Stange, Eberhard Waldhör, Michael Moscherosch, Wolfgang Kaim | Requires cookie* | | | Title
| Variable Structure of the Cu2S2 Core in Doubly Thiolate-Bridged Dicopper(I) Complexes. An X-Ray Crystallographic, Electrochemical and EPR Study of (dmp)2 (o-CH3 C6H4S)2Cu2 , dmp = 2,9-Dimethyl-l,10-phenanthroline, and a Comment on the Nature of Phenanthroline-Containing "Cu(0)" Complexes  | | | | Abstract
| The molecular and crystal structure of the dicopper(I) complex (dm p)2(M-o-CH3C6H4S)2Cu2 (1), dmp = 2,9-dim ethyl-l,10-phenanthroline, has been deter mined. With Cu/S/Cu and S/Cu/S bond angles between 80 and 100°, the planar structure of the central CuSCuS four-membered ring is much more symmetric for 1 as compared to the analogous complex 2 of unsubstituted 1,10-phenanthroline which has a folded Cu2S2 core with bond angles between 67 and 108°. This result illustrates a considerable structural flexi bility of the LCu(m-SR)2CuL entity which is being discussed as a possible model for CuA centers of cytochrome c oxidase or nitrous oxide reductase. Oxidation of both com plexes 1 and 2 remains irreversible even at cyclovoltammetric scan rates o f 1 V/s. However, the methyl substitution in complex 1 causes increased reversibility of the electronically coupled dmp-based reduction processes. Accordingly, the EPR spectrum of l -* is characterized by hyper-fine splitting from dmp--and a relatively small 63 " Cu coupling of 0.53 mT. The stabilization of 2,9-disubstituted 1,10-phenanthroline radical anions by coordination to Cu(I) is also dem onstrated by detection of a single broad EPR line at g 2.0028 for the formal "C u(0)" complex Cu(dpp)2 = CuI(dpp_-)(dpp), dpp = 2,9-diphenyl-l,10-phenanthroline. While the EPR signal of Cu(dpp)2 loses intensity on cooling, possibly due to dimerization and spin-pairing, the distorted tetrahedral configuration with essential orthogonal arrangement of dpp jz systems seem s to disfavour an intramolecular electron hopping. | | | |
Reference
| (Z. Naturforsch. 50b, 115—122 [1995]; received July 25 1994) | | | |
Published
| 1995 | | | |
Keywords
| Crystal Structure, Copper Complexes, Sulfur Ligands, 1, 10-Phenanthrolines, EPR Spectra | | | |
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| ZNB-1995-50b-0115 | | | | Volume
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