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

Abstract

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.