Oxygen atom exchange in reactions of OH radicals with NO and ClO

Oxygen atom exchange between OH and (NO, ClO) has been investigated by ab initio molecular orbital methods. Reactants and transition states were fully optimized with second-order Møller–Plesset perturbation and coupled-cluster methods using the 6-311G(3df,3pd) basis set. Theoretical results predicted at these levels of theory suggest that the reaction between OH and NO should exchange rapidly because the barrier to isomerization is significantly less than the O–N bond dissociation energy of the HONO adduct. For the OH + ClO reaction, the barrier to isomerization is estimated to be 3.1 kcal mol−1 above the O–Cl bond dissociation energy of the HOClO adduct.