DFT study on activation of carbon dioxide by (tBuArN)3MN (MNb,V,Ta): the electronic structure and activity

The reaction mechanism for the reduction of CO2 gas activated by (tBuArN)3MN was studied by the means of density functional theory (DFT) calculations. The calculations indicated that this reaction has a two step reaction mechanism. From our calculations, we found that (tBuArN)3TaN held the best activity among the three (tBuArN)3MN complexes studied. Our results also indicated that the reaction of (tBuArN)3MN with CO2 occurred under orbital control involving the HOMO-3 orbital of (tBuArN)3MN, which could give higher overlapping with the LUMO of the CO2 molecule. The substitutions on the amino donor ligands studied here took larger effect on the HOMO structure of the (tBuArN)3MN molecules. The electronic structure of the (tBuArN)3MN complexes also showed their ability for activating CO2 molecules, in the order of M = V < Nb < Ta.