Mechanism of Carbon Monoxide Induced N–N Bond Cleavage of Nitrous Oxide Mediated by Molybdenum Complexes: A DFT Study

The detailed mechanism of CO-induced N–N bond cleavage of N₂O mediated by molybdenum complexes leading to the nitrosyl isocyanate complex has been investigated via density functional theory (DFT) calculations at the B3LYP level. On the basis of the calculations, we proposed a new reaction mechanism of CO-induced N–N bond cleavage of N₂O with an overall free energy barrier of 23.6 kcal/mol, significantly lower than that of the reaction mechanism (42.2 kcal/mol) proposed by Sita et al. The calculations also indicated that CO-induced N–N bond cleavage of N₂O is competitive with oxygen atom transfer (OAT) to carbon monoxide due to the comparable free energy barriers. The metal-bound carbonyl complex obtained from OAT can be recycled to give more nitrosyl isocyanate complexes. In addition, we demonstrated why the analogous tungsten complex cannot give the nitrosyl isocyanate complex via CO-induced N–N bond cleavage of N₂O. The calculations are consistent with experimental observations.