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)

• Published in: Inorganic chemistry Vol. 55; no. 23; pp. 12137 - 12148
• Main Authors: Wu, Bing, Wilding, Matthew J. T, Kuppuswamy, Subramaniam, Bezpalko, Mark W, Foxman, Bruce M, Thomas, Christine M
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 05-12-2016; American Chemical Society (ACS)
• Subjects: Chemistry
• ISSN: 0020-1669; 1520-510X
• DOI: 10.1021/acs.inorgchem.6b01543

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(XylNP i Pr2)3 (1) and Ti­(XylNP i Pr2)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(XylNP i Pr2)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 C 3-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.