A theoretical study of the 2NCOÂ +Â 2N2H reaction

The singlet and triplet potential surfaces of the 2NCO + 2N2H reaction have been investigated at the B3LYP/6-311G (d,p) level. The single-point energy calculations are performed at the high-level CCSD (T)/6-311G (d,p) for more accurate energy values. DFT calculations reveal the reaction mechanism to be mainly a barrierless addition of 2NCO to 2N2H leading to an intermediate 1im3 (OCN-N2H) on the singlet potential surface. The adduct 1im3 goes through an H shift from N2H to NCO, forming the product of HNCO and N2. Due to the higher barrier of initial association, the reaction is more difficult on the triplet potential surface.