Exploring Trends in Metal–Metal Bonding, Spectroscopic Properties, and Conformational Flexibility in a Series of Heterobimetallic Ti/M and V/M Complexes (M = Fe, Co, Ni, and Cu)

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• 作者：Bing Wu ; Matthew J. T. Wilding ; Subramaniam Kuppuswamy ; Mark W. Bezpalko ; Bruce M. Foxman ; Christine M. Thomas
• 刊名：Inorganic Chemistry
• 出版年：2016
• 出版时间：December 5, 2016
• 年：2016
• 卷：55
• 期：23
• 页码：12137-12148
• 全文大小：581K
• ISSN：1520-510X

文摘

To understand the metal–metal bonding and conformational flexibility of first-row transition metal heterobimetallic complexes, a series of heterobimetallic Ti/M and V/M complexes (M = Fe, Co, Ni, and Cu) have been investigated. The titanium tris(phosphinoamide) precursors ClTi(XylNPⁱPr₂)₃ (1) and Ti(XylNPⁱPr₂)₃ (2) have been used to synthesize Ti/Fe (3), Ti/Ni (4, 4^THF), and Ti/Cu (5) heterobimetallic complexes. A series of V/M (M = Fe (7), Co (8), Ni (9), and Cu (10)) complexes have been generated starting from the vanadium tris(phosphinoamide) precursor V(XylNPⁱPr₂)₃ (6). The new heterobimetallic complexes were characterized and studied by NMR spectroscopy, X-ray crystallography, electron paramagnetic resonance, and Mössbauer spectroscopy, where applicable, and computational methods (DFT). Compounds 3, 4^THF, 7, and 8 are C₃-symmetric with three bridging phosphinoamide ligands, while compounds 9 and 10 adopt an asymmetric geometry with two bridging phosphinoamides and one phosphinoamide ligand bound η² to vanadium. Compounds 4 and 5, on the other hand, are asymmetric in the solid state but show evidence for fluxional behavior in solution. A correlation is established between conformational flexibility and metal–metal bond order, which has important implications for the future reactivity of these and other heterobimetallic molecules.