Influence of Copper Oxidation State on the Bonding and Electronic Structure of Cobalt鈥揅opper Complexes

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• 作者：Reed J. Eisenhart ; Rebecca K. Carlson ; Laura J. Clouston ; Victor G. Young Jr. ; Yu-Sheng Chen ; Eckhard Bill ; Laura Gagliardi ; Connie C. Lu
• 刊名：Inorganic Chemistry
• 出版年：2015
• 出版时间：December 7, 2015
• 年：2015
• 卷：54
• 期：23
• 页码：11330-11338
• 全文大小：526K
• ISSN：1520-510X

文摘

Heterobimetallic complexes that pair cobalt and copper were synthesized and characterized by a suite of physical methods, including X-ray diffraction, X-ray anomalous scattering, cyclic voltammetry, magnetometry, electronic absorption spectroscopy, electron paramagnetic resonance, and quantum chemical methods. Both Cu(II) and Cu(I) reagents were independently added to a Co(II) metalloligand to provide (py₃tren)CoCuCl (1-Cl) and (py₃tren)CoCu(CH₃CN) (2-CH₃CN), respectively, where py₃tren is the triply deprotonated form of N,N,N-tris(2-(2-pyridylamino)ethyl)amine. Complex 2-CH₃CN can lose the acetonitrile ligand to generate a coordination polymer consistent with the formula 鈥?py₃tren)CoCu鈥?(2). One-electron chemical oxidation of 2-CH₃CN with AgOTf generated (py₃tren)CoCuOTf (1-OTf). The Cu(II)/Cu(I) redox couple for 1-OTf and 2-CH₃CN is reversible at 鈭?.56 and 鈭?.33 V vs Fc⁺/Fc, respectively. The copper oxidation state impacts the electronic structure of the heterobimetallic core, as well as the nature of the Co鈥揅u interaction. Quantum chemical calculations showed modest electron delocalization in the (CoCu)⁺⁴ state via a Co鈥揅u 蟽 bond that is weakened by partial population of the Co鈥揅u 蟽 antibonding orbital. By contrast, no covalent Co鈥揅u bonding is predicted for the (CoCu)⁺³ analogue, and the d-electrons are fully localized at individual metals.