The potential energy surface (PES) of a [C2,H2,N,O] system in its electronic doublet ground state
has been investigated using density functional theory method, at B3LYP/6-311++G(3df,2p)// B3LYP/6-
311++G-(d,p) level. Twelve stable intermediate radicals including trans-nitrosoethenyl 1, cis-nitrosoethenyl
2, iminoketenyl 11, and aminoketenyl 12 radicals have been located. Other stationary points on the PES
formed from hydrogen migration and dissociation channels of these intermediates have been identified.
Barrier heights, vibrational wavenumbers and moments of inertia were then utilized in the calculations of
rate constants using quantum Rice-Ramsperger-Kassel (QRRK) theory. The total rate constant is found to
increase with increase of temperature. At temperatures below 1000 K, only a rapid equilibrium is established
between the reactants and the trans-nitrosoethenyl 1 radical which, in turn, suggests an absence of a reaction
at low temperatures. HCO + HCN is found to be the predominant product at high temperatures and it
involves five isomers of [C2,H2,N,O] system as intermediates with the formation of the four-membered ring
3 as the rate determining step. The rate constant for the formation of HCO + HNC is found to be 2 orders of
magnitude lower than that for HCO + HCN. The total rate constant is pressure independent at low pressures
up to atmospheric pressure. The calculated total rate constant at 2000 K and 1 atm pressure is 7.9 ?? 104 cm
3 mol-1 s-1.
