Technische Universität Berlin, Department of Chemistry: Metalorganics and Inorganic Materials, Sekr. C2, Strasse des 17. Juni 135, 10623, Berlin, Germany.
Department of Chemical & Biological Engineering, University of Wisconsin-Madison, 1415 Engineering Drive, Madison, WI, 53706, USA.
Angew Chem Int Ed Engl. 2017 Mar 20;56(13):3699-3702. doi: 10.1002/anie.201700625. Epub 2017 Feb 27.
The first single-component N-heterocyclic silylene borane 1 (LSi-R-BMes ; L=PhC(N Bu) ; R=1,12-xanthendiyl spacer; Mes=2,4,6-Me C H ), 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 O , N O, or CO , and formation of silanethione borane 4 from reaction with S . The Si center in 1 undergoes immediate hydrogenation if exposed to H at 1 atm pressure in benzene, affording the silane borane 5-H , L(H )Si-R-BMes . Remarkably, no H activation occurs if the single silylene LSiPh and Mes B intermolecularly separated are exposed to dihydrogen. Unexpectedly, the pre-organized Si-B separation in 1 enables a metal-free dehydrogenation of H O to give the silanone-borane 3 as reactive intermediate.
首个单一组分 N-杂环硅亚基硼烷 1（LSi-R-BMes；L=PhC(N Bu)；R=1,12-蒽二基间隔基；Mes=2,4,6-Me C H），作为小分子活化中的受阻路易斯对（FLP），可收率为 65%合成。其 HOMO 在很大程度上定域在硅（II）原子上，而 LUMO 主要具有硼 2p 特征。在小分子活化中，1 允许通过与 O、N O 或 CO 反应，形成具有 Si=O→B 相互作用的分子内硅酮-硼烷 3，并且通过与 S 反应形成硅硫代硼烷 4。如果在苯中在 1 大气压下暴露于 H，Si 中心会立即加氢，生成硅烷硼烷 5-H，L（H）Si-R-BMes。值得注意的是，如果将单硅亚基 LSiPh 和 Mes B 分子间分离并暴露于氢气，则不会发生 H 活化。出乎意料的是，1 中预先组织的 Si-B 分离能够使 H O 进行无金属脱氢，得到作为反应性中间体的硅酮-硼烷 3。
