Atmospheric reaction between the HS radical and chlorine

The mechanism and the kinetics of the reaction between HS and Cl ₂ leading to HSCl and Cl were studied theoretically. The effect of the complete basis set limit (CBS) was included by extrapolating the results obtained with cc-pVDZ, cc-pVTZ and cc-pVQZ correlation consistent basis sets functions. At the highest level of calculation, CCSD(T), the calculated rate constant is 1.0×10 ^-12 cm ³ molecule ^-1 s ^-1. The activation Gibbs free energy was calculated to be 7.4 kcal/mol, which is only 0.2 kcal/mol above the value determined experimentally. The enthalpy and Gibbs free energies of the reaction are -6.9 and -6.5 kcal/mol, respectively.