A Theoretical Study of the Mechanism and Kinetics of the Thermal Decomposition of Carbamoyl Azide

Abstract

The mechanism and kinetics of the thermal decomposition of carbamoyl azide N3CONH2 were studied using the B3LYP/6-311++G(d,p) level of theory. All species involved in the pyrolysis reaction were fully optimised and corrected for zero-point energies. The results showed that the initial step mainly involved the non-homolytic fission of the N–N bond. Either the imine NHCONH or the nitrene NCONH2 could be formed by the release of molecular N2. Calculation confirmed that the formation of the nitrene is the dominant process. Then, extrusion of CO from the nitrene will produce NNH2 which decomposes to N2 and H2 as the most stable products. Transition states (TSs) are obtained and characterised on the potential energy surfaces throughout the reaction. The existence of TSs on the corresponding potential energy surfaces is ascertained by performing intrinsic reaction coordinate calculations. In all steps, comparing the bond dissociation energies suggests which one is stronger during the initiation of thermolysis. The calculated rate constant using transition state theory is 1.15 × 10−28 s−1 at 298.15 K and 1.00 atm.