Cobalt(I)-Catalyzed Transformation of Si–H Bonds: H/D Exchange in Hydrosilanes and Hydrosilylation of Olefins
Lars Denker, Daniela Wullschläger, Juan Pablo Martínez, Stanisław Świerczewski, Bartosz Trzaskowski, Matthias Tamm, René Frank
Abstract
High Resolution Image Download MS PowerPoint Slide The amino imidazolin-2-imine ligand [HAmIm, 1,2-(DippNH)–C 6 H 4 –N═C(N i PrCMe) 2 ] is employed in the synthesis of the paramagnetic cobalt(I) arene complex Co(AmIm)(η 6 -C 6 H 6 ). The latter was found to be a highly efficient (pre)catalyst in H/D exchange reactions with deuterium (D 2 ) in hydrosilanes. The scope comprises primary to tertiary silanes at a low catalyst loading of 1 mol %. Additionally, the same cobalt(I) arene complex was able to catalyze hydrosilylation reactions of terminal olefins with primary to tertiary silanes at low catalyst loadings of 0.5 mol %. The scope of hydrosilylation includes intramolecular hydrosilylation to produce silacarbocycles and multiple hydrosilylation with primary silanes. The mechanistic investigation includes numerous control experiments for both H/D exchange and hydrosilylation. Isolated (trapped) cobalt(III) hydride silyl complexes (including X-ray crystallographic authentication) are presented for primary to tertiary Si–H entities, which demonstrates a wide scope of Si–H bond activation by the low-valent Co(AmIm) core. The experimental results are strongly corroborated by density functional theory calculations, which explore the possible reaction mechanisms of studied reactions.