Gaseous reaction mechanism between two H(2)CN radicals.

The self-recombination of the methylene amidogen radical (H(2)CN) is known to be fast and should play an important role in determining the concentration of H(2)CN radicals in both combustion and astrophysical processes. The rate constants of H(2)CN + H(2)CN have been determined by previous experiments, whereas its detailed evolution process and product distribution are still unclear. In this work, by means of quantum chemical and master equation calculations, we for the first time explored theoretically the potential energy surface and kinetics of the H(2)CN + H(2)CN reaction. At the CCSD(T)/6-311++G(2df,p), CCSD(T)/aug-cc-pVTZ and Gaussian-3 single-point levels based on the B3LYP/6-31++G(d,p) structures, the dominant channel was found to be () H(2)CN + H(2)CN --> H(2)CNNCH(2) () --> r-CH(2)NNCH(2) () --> N(2) + C(2)H(4) () with a zero overall barrier. The calculated rate constants are in agreement with available experiments. Of particular interest, since the formed product involves molecular nitrogen, the H(2)CN + H(2)CN reaction might have important contribution to the nitrogen-recycling in a number of conflagrant and astrophysical processes.