Carbon dioxide reduction by pincer rhodium eta(2)-dihydrogen complexes: Hydrogen-binding modes and mechanistic studies by density functional theory calculations

摘要

Density functional theory (DFT) calculations using the KMLYP method on a series of pincer PCP-rhodium dihydrogen complexes have been employed to model and examine the proposed mechanisms for the pincer PCP-rhodium complexes mediated hydrogenation of carbon dioxide (CO2). The relative energies of dihydrogen rotamers and dihydride isomers were evaluated together with T-1 values to determine the molecular structures of these complexes. We have investigated possible pathways for the CO2 reduction processes involving the formation of rhodium dihydride species. Although the dihydrogen complexes are more stable than the corresponding dihydride isomers, the reduction of CO2 has to proceed through the dihydride structures.