Hydrogenation of CO₂ by a Tripodal Palladium Pincer Complex

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 CO2. Through experimental and theoretical studies, we demonstrated that our catalyst operates via a hydrogen activation mechanism involving the heterolytic splitting of H2 between the sterically demanding trigonal pyramidal palladium fragment and the loosely coordinated PCy3 ligand. Beyond the fundamental interest in understanding the reactivity of these compounds, our study describes a practical catalyst for CO2 hydrogenation, demonstrating high turnover numbers (TON = 3.5 × 103) under mild reaction conditions.