The reaction of methylidyne radical with molecule NO~2 was studied theoretically by using MP2(FULL)/6-31G(d) and QCISD(T)/6-31G(d). The reaction paths were found both for the formation of intermediates and the dissociation of some intermediates to form the products. The energies and structures of important intermediates and transition states were reported for the first time. The reaction path was followed from the transition state both to the reactant and the product direction by using the intrinsic reaction coordinate (IRC) method. By thermodynamic and mechanic analysis, the main reaction path channel was detected, the main products were found, and branching ratio was calculated, which was in good agreement with the experimental results.

Key words: NITROGEN OXIDE, HYDROCARBONS, FREE RADICAL REACTION, REACTION KINETICS, ACTIVATION ENERGY, TRANSITION STATE