Theoretical study on the mechanism of the reaction of CF(3)S with NO(2).

The singlet potential energy surface for the CF3S + NO2 reaction has been theoretically investigated using the B3LYP/6-311+G(3df) level of theory. The geometries, vibrational frequencies, and zero-point energies of all stationary points involved in the title reaction have been examined. More accurate energies of stationary points were obtained using ab initio G3//B3LYP and CBS-QB3 composite methods. The results show that the initial addition of CF3S with NO2 leads to CF3SNO2 or CF3SONO intermediates, which are formed without an electronic barrier. CF3SNO2 can easily isomerizes to CF3SONO, while CF3SONO readily isomerizes to CF3S(O)NO or dissociates to CF3SO + NO, which are the major products of the title reaction. Reaction channels leading to the formation the CF3O + SNO and CF2S + FNO2 products are highly improbable processes due to high energy barriers involved. We have also computed heats of formation for CF3SNO2, CF3SONO, and CF3S(O)NO intermediates. It was found that the most stable is the cis-perpendicular form of CF3SONO isomer with DeltaH(f,0)0 = -243.6 kcal mol-1.