Theoretical calculations on the reactions of NO2 with Sc, Ti and V

Density functional calculations have been performed to describe the ground-state reactions between NO2 and Sc, Ti and V atoms. We have obtained smooth energy curves along the reaction coordinate and found no barrier. The reaction products form a quite strong MO–NO complex via a 1δ–2π∗ bond at the end of the reactions. The reactions are initiated by mutual electron donations between the metal atom and the NO2 molecule. Considerable 4s–3d hybridization takes place continuously on the metal atoms in the following stages to facilitate the formation of the ground-state metal oxides in the case of Ti and V. For Sc the calculations revealed that the final complex requires formation of the lowest excited ScO state compensated in energy by the large stability of the complex. To elucidate the complete reaction mechanism ingredients of both the so-called electron transfer and surface crossing models have to be invoked.