An air-stable, Zn2+-based catalyst for hydrosilylation of alkenes and alkynes

Abstract

Hydrosilylation of CC double and CC triple bonds is one of the most widely used processes in organosilicon chemistry, mostly catalyzed by Pt-based complexes. We report here the synthesis of an air-stable dicationic Zn²⁺-based complex in a hemilabile tris(2-methyl-6-pyridylmethyl) phosphine (TmPPh) ligand, 1²⁺[B(C₆F₅)₄]₂. When heated, 1²⁺[B(C₆F₅)₄]₂ activates Si–H bonds reversibly via ligand/metal cooperation between Lewis acidic Zn²⁺ and Lewis basic N centers in a frustrated Lewis pair (FLP) type fashion. Consequently, 1²⁺[B(C₆F₅)₄]₂ was found to be an effective catalyst for hydrosilylation reactions of CC double and CC triple bonds. Remarkably, these hydrosilylation reactions can be loaded under aerobic conditions, as well as, in some cases, work under neat conditions. The mechanism of the activation of the Si–H bond and the hydrosilylation reaction is proposed based on experiments and density functional theory (DFT) calculations.