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.