title: 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).
abstract: 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, 4THF), 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, 4THF, 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 η2to 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.
authors: Department of Chemistry, Brandeis University , 415 South Street, Waltham, Massachusetts 02454, United States.
authors: Bing
authors: B
authors: Wu
authors: Department of Chemistry and Chemical Biology, Harvard University , 12 Oxford Street, Cambridge, Massachusetts 02138, United States.
authors: Matthew J T
authors: MJ
authors: Wilding
authors: Department of Chemistry, Brandeis University , 415 South Street, Waltham, Massachusetts 02454, United States.
authors: Subramaniam
authors: S
authors: Kuppuswamy
authors: Department of Chemistry, Brandeis University , 415 South Street, Waltham, Massachusetts 02454, United States.
authors: Mark W
authors: MW
authors: Bezpalko
authors: Department of Chemistry, Brandeis University , 415 South Street, Waltham, Massachusetts 02454, United States.
authors: Bruce M
authors: BM
authors: Foxman
authors: Department of Chemistry, Brandeis University , 415 South Street, Waltham, Massachusetts 02454, United States.
authors: Christine M
authors: CM
authors: Thomas