Flexible proton-responsive ligand-based Mn(i) complexes for CO2 hydrogenation: a DFT study†
A series of flexible proton-responsive group substituted N^N-bidentate ligand based Mn(I) complexes have been studied for base free CO2 hydrogenation. We show here that proton responsive ligands play a critical role in base free CO2 hydrogenation. Our calculated reaction free energy barrier values for heterolytic H2 cleavage show that such flexible proton-responsive ligands require a very low activation energy (∼3 kcal mol−1) barrier. Such flexible proton responsive ligands improve the strong dihydrogen (H⋯H) bonding, which in turn improves heterolytic H2 cleavage − an important step for base free CO2 hydrogenation. Therefore, we believe that such flexible proton responsive ligand-substituted metal complexes can be promising for base free CO2 hydrogenation reactions.