title: A Pentacoordinate Mn(II) Precatalyst That Exhibits Notable Aldehyde and Ketone Hydrosilylation Turnover Frequencies.
abstract: Heating (THF)2MnCl2 in the presence of the pyridine-substituted bis(imino)pyridine ligand, (PyEt)PDI, allowed preparation of the respective dihalide complex, ((PyEt)PDI)MnCl2. Reduction of this precursor using excess Na/Hg resulted in deprotonation of the chelate methyl groups to yield the bis(enamide)tris(pyridine)-supported product, (κ(5)-N,N,N,N,N-(PyEt)PDEA)Mn. This complex was characterized by single-crystal X-ray diffraction and found to possess an intermediate-spin (S = (3)/2) Mn(II) center by the Evans method and electron paramagnetic resonance spectroscopy. Furthermore, (κ(5)-N,N,N,N,N-(PyEt)PDEA)Mn was determined to be an effective precatalyst for the hydrosilylation of aldehydes and ketones, exhibiting turnover frequencies of up to 2475 min(-1) when employed under solvent-free conditions. This optimization allowed for isolation of the respective alcohols and, in two cases, the partially reacted silyl ethers, PhSiH(OR)2 [R = Cy and CH(Me)((n)Bu)]. The aldehyde hydrosilylation activity observed for (κ(5)-N,N,N,N,N-(PyEt)PDEA)Mn renders it one of the most efficient first-row transition metal catalysts for this transformation reported to date.
authors.affiliation: School of Molecular Sciences, Arizona State University , Tempe, Arizona 85287, United States.
authors.forename: Chandrani
authors.initials: C
authors.lastname: Ghosh
authors.affiliation: School of Molecular Sciences, Arizona State University , Tempe, Arizona 85287, United States.
authors.forename: Tufan K
authors.initials: TK
authors.lastname: Mukhopadhyay
authors.affiliation: School of Molecular Sciences, Arizona State University , Tempe, Arizona 85287, United States.
authors.forename: Marco
authors.initials: M
authors.lastname: Flores
authors.affiliation: School of Molecular Sciences, Arizona State University , Tempe, Arizona 85287, United States.
authors.forename: Thomas L
authors.initials: TL
authors.lastname: Groy
authors.affiliation: School of Molecular Sciences, Arizona State University , Tempe, Arizona 85287, United States.
authors.forename: Ryan J
authors.initials: RJ
authors.lastname: Trovitch