Frustrated Lewis Pair Catalyzed Reduction of Carbon Dioxide Using Hydroboranes: New DFT Mechanistic Insights

Catalytic CO2 reduction is attractive for the sustainable production of value-added fuels and chemicals. Prevented by an unclear mechanistic picture, only a few frustrated Lewis pair (FLP) catalysts are known for the efficient CO2 reduction under mild conditions using hydroboranes as reductant. For the first time, based on extensive DFT calculations, very efficient mechanisms for all steps of the FLP-catalyzed reduction of CO2 to various products of boryl formate, H2CO, bis(boryl) acetal and methoxyl borane are revealed. Zwitterionic B/P FLP-H2CO adducts are confirmed as active catalyst via the Lewis-basic CH2O "oxide" center. Strong O and N Lewis-bases are very active in promoting hydride transfer from hydroboranes to CO2 and strongly bound to the boryl group of reduced species. This can be modulated by Lewis acids in FLP catalysts for well-balanced catalytic activity, which is crucial for further design of novel catalytic process.