Electron-rich platinum single sites anchored on sulfur-doped covalent organic frameworks for boosting anti-Markovnikov hydrosilylation of alkenes

Selective catalytic hydrosilylation of alkenes for the synthesis of organosilicon products is very important in the fine chemical industry. Nevertheless, conventional Pt-based homogeneous catalysts are hindered by their low reaction selectivity, catalyst residues, and Pt leaching. In this study, a series of covalent organic frameworks (COFs)-anchored single-site Pt catalysts for achieving high-performance alkene hydrosilylation were prepared, and comprehensive characterizations confirmed that the actual coordination environment of Pt active sites is NSPt-Cl2. The resulting Pt(0.75%)@BTT-BPh-COF catalyst exhibited superior activity for the anti-Markovnikov hydrosilylation of alkenes with an excellent selectivity (>99%) under solvent-free conditions. Experimental and theoretical analysis revealed that the excellent catalytic performance is attributed to the effective charge transfer and strong coordination effect between Pt and S, N-co-doped COFs, which is conducive to the generation of electron-rich and highly active Pt single sites. High catalyst stability was maintained during recycling experiments due to the strong anchoring effect of the COFs support on atomically dispersed Pt single sites as well as the pore confinement effect. This study not only describes the precise design for the state-of-the-art catalysts with accurate active sites but also affords in-depth insights into alkene hydrosilylation.