title: An Intramolecular Silylene Borane Capable of Facile Activation of Small Molecules, Including Metal-Free Dehydrogenation of Water.
abstract: The first single-component N-heterocyclic silylene borane 1 (LSi-R-BMes2; L=PhC(NtBu)2; R=1,12-xanthendiyl spacer; Mes=2,4,6-Me3C6H2), acting as a frustrated Lewis pair (FLP) in small-molecule activation, can be synthesized in 65 % yields. Its HOMO is largely localized at the silicon(II) atom and the LUMO has mainly boron 2p character. In small-molecule activation 1 allows access to the intramolecular silanone-borane 3 featuring a Si=O→B interaction through reaction with O2, N2O, or CO2, and formation of silanethione borane 4 from reaction with S8. The SiIIcenter in 1 undergoes immediate hydrogenation if exposed to H2at 1 atm pressure in benzene, affording the silane borane 5-H2, L(H2)Si-R-BMes2. Remarkably, no H2activation occurs if the single silylene LSiPh and Mes3B intermolecularly separated are exposed to dihydrogen. Unexpectedly, the pre-organized Si-B separation in 1 enables a metal-free dehydrogenation of H2O to give the silanone-borane 3 as reactive intermediate.
authors.affiliation: Technische Universität Berlin, Department of Chemistry: Metalorganics and Inorganic Materials, Sekr. C2, Strasse des 17. Juni 135, 10623, Berlin, Germany.
authors.forename: Zhenbo
authors.initials: Z
authors.lastname: Mo
authors.affiliation: Department of Chemical & Biological Engineering, University of Wisconsin-Madison, 1415 Engineering Drive, Madison, WI, 53706, USA.
authors.forename: Tibor
authors.initials: T
authors.lastname: Szilvási
authors.affiliation: Technische Universität Berlin, Department of Chemistry: Metalorganics and Inorganic Materials, Sekr. C2, Strasse des 17. Juni 135, 10623, Berlin, Germany.
authors.forename: Yu-Peng
authors.initials: YP
authors.lastname: Zhou
authors.affiliation: Technische Universität Berlin, Department of Chemistry: Metalorganics and Inorganic Materials, Sekr. C2, Strasse des 17. Juni 135, 10623, Berlin, Germany.
authors.forename: Shenglai
authors.initials: S
authors.lastname: Yao
authors.affiliation: Technische Universität Berlin, Department of Chemistry: Metalorganics and Inorganic Materials, Sekr. C2, Strasse des 17. Juni 135, 10623, Berlin, Germany.
authors.forename: Matthias
authors.identifier: 0000-0002-9873-4103
authors.initials: M
authors.lastname: Driess
keywords: N-heterocyclic silylene; dehydrogenation; dihydrogen activation; frustrated Lewis pairs; silanone