title: Preparation and hydrosilylation activity of a molybdenum carbonyl complex that features a pentadentate bis(imino)pyridine ligand.
abstract: Attempts to prepare low-valent molybdenum complexes that feature a pentadentate 2,6-bis(imino)pyridine (or pyridine diimine, PDI) chelate allowed for the isolation of two different products. Refluxing Mo(CO)6 with the pyridine-substituted PDI ligand, (PyEt)PDI, resulted in carbonyl ligand substitution and formation of the respective bis(ligand) compound ((PyEt)PDI)2Mo (1). This complex was investigated by single-crystal X-ray diffraction, and density functional theory calculations indicated that 1 possesses a Mo(0) center that back-bonds into the π*-orbitals of the unreduced PDI ligands. Heating an equimolar solution of Mo(CO)6 and the phosphine-substituted PDI ligand, (Ph2PPr)PDI, to 120 °C allowed for the preparation of ((Ph2PPr)PDI)Mo(CO) (2), which is supported by a κ(5)-N,N,N,P,P-(Ph2PPr)PDI chelate. Notably, 1 and 2 have been found to catalyze the hydrosilylation of benzaldehyde at 90 °C, and the optimization of 2-catalyzed aldehyde hydrosilylation at this temperature afforded turnover frequencies of up to 330 h(-1). Considering additional experimental observations, the potential mechanism of 2-mediated carbonyl hydrosilylation is discussed.
authors.affiliation: Department of Chemistry & Biochemistry, Arizona State University , Tempe, Arizona 85287, United States.
authors.forename: Raja
authors.initials: R
authors.lastname: Pal
authors.forename: Thomas L
authors.initials: TL
authors.lastname: Groy
authors.forename: Amanda C
authors.initials: AC
authors.lastname: Bowman
authors.forename: Ryan J
authors.initials: RJ
authors.lastname: Trovitch