Hydrogenation of CO₂ by a Tripodal Palladium Pincer Complex

Abstract

This study presents the hydrogenation of carbon dioxide to formate catalyzed by a palladium catalyst based on a tripodal pincer ligand. Our work demonstrates how this catalyst design facilitates the formation of more hydridic anionic trigonal bipyramidal Pd−H species, efficiently promoting hydride transfer to CO 2 . Through experimental and theoretical studies, we demonstrated that our catalyst operates via a hydrogen activation mechanism involving the heterolytic splitting of H 2 between the sterically demanding trigonal pyramidal palladium fragment and the loosely coordinated PCy 3 ligand. Beyond the fundamental interest in understanding the reactivity of these compounds, our study describes a practical catalyst for CO 2 hydrogenation, demonstrating high turnover numbers (TON = 3.5 × 10 3 ) under mild reaction conditions.