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.