Ab initio study on the dissociation pathways of XSO2 (XCl, F) radicals

The dissociation dynamics of XSO2 (XF, Cl) radicals has been investigated using an ab initio method. At the QCISD/6–31G∗ + ΔZPE level theory, halogen extrusion from XSO2 is predicted to be endothermic by 28.7 kcal mol−1 for XF and exothermic by 7.7 kcal mol−1 for XCl, respectively. The bond dissociation energies computed for FSO2 using G2, G2(MP2), CBS-Q and CBS-4 theories are consistent with that calculated at the QCISD/6–31G∗+ΔZPE level of theory. The atmospheric implication of the computational results is discussed.