DFT study on activation of carbon dioxide by (tBuArN)(3)M N (M=Nb, V, Ta): the electronic structure and activity

The reaction mechanism for the reduction of CO2 gas activated by (tBuArN)(3)M N 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)(3)Ta N held the best activity among the three (tBuArN)(3)M N complexes studied. Our results also indicated that the reaction of (tBuArN)(3)M N with CO2 occurred under orbital control involving the HOMO-3 orbital of (tBuArN)(3)M N, 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)(3)M N molecules. The electronic structure of the (tBuArN)(3)M N complexes also showed their ability for activating CO2 molecules, in the order of M = V < Nb < Ta.