Computational Study of the Reaction of the Methylsulfonyl Radical, CH3S(O)2, with NO2

The mechanism of the reaction between the methylsulfonyl radical, CH3S(O)(2), and NO2 is examined using density functional theory and ab initio calculations. Two stable association intermediates, CH3SNO2 and CH3S(O) ONO, may be formed through the attack of the nitrogen or the oxygen atom of NO2 radical to the S atom. Interisomerization and decomposition of these intermediates are investigated using high level energy methods and specifically, CCSD(T), CBS-QB3, and G3//B3LYP. The computational investigation indicates that the lowest energy reaction pathway leads to the products CH3S(O) + NO, through the decomposition of the most stable association adduct CH3S(O) ONO. This result fully supports the relevant assumption of Ray et al. (Ray et al., J. Phys. Chem. 1996, 100, 8895], on which the experimental evaluation of the rate constant was based, namely that CH3S(O)(3) + NO are the most probable products of the reaction CH3S(O)(2) + NO2. (C) 2014 Wiley Periodicals, Inc.