A THEORETICAL-STUDY OF THE H+SO2 REACTION

Ab initio UHF and MP2 calculations have been used to characterize the relative stabilities, equilibrium geometries, and harmonic frequencies of the intermediates involved in the H + SO2 reaction. Calculations for the entrance channel potentials at the MP2/DZP level of theory indicate pure repulsion for planar attack (2A' surface) by the H atom on the S atom of SO2 and an 11 kcal/mol barrier to the nonplanar (2A'' surface) attack. Much larger barriers are predicted for the formation of the HOSO adducts on this surface. Implications to experiments involving the reaction of SO2 with translationally hot H atoms are discussed.