Bidentate N‐based Ligands for Highly Reusable, Ligand‐coordinated, Supported Pt Hydrosilylation Catalysts
Abstract A significant challenge in designing supported metal‐ligand catalysts for solution‐phase reactions is the stabilization of the metal active sites against leaching into solution. Here, we examine alkene hydrosilylation reactions as model systems to improve the stability of highly dispersed Pt using a metal‐ligand coordination strategy on high surface area oxide supports. By evaluating a series of bidentate N‐based ligands, we demonstrate several design strategies to improve stability of the highly dispersed Pt 2+ centers against leaching, while maintaining a high level of catalytic activity, selectivity, and recyclability for alkene hydrosilylation batch reactions under mild conditions. These involve a bi‐functional approach to ligand design, which considers interaction to the support and a well‐defined coordination environment for the metal active site. Three strategies are reported: modifying ligands for stronger interaction with oxide surfaces, mixing ligands, and pre‐depositing an “anchoring ligand” to the support before loading the metal‐ligand catalyst. Each of these is successful in enhancing Pt recyclability. Particularly, two Pt‐phenanthroline catalysts exhibit excellent reusability for multiple batch reaction cycles, due to high stability of the active Pt species. Addressing the active site leaching problem significantly enhances the utility of ligand‐coordinated supported metal catalysts as highly stable and selective catalysts for solution‐phase reactions.