THEORETICAL ESTIMATE OF THE ENTHALPY OF FORMATION OF HSO AND THE HSO SOH ISOMERIZATION ENERGY

The enthalpy of formation of HSO is estimated to be -5.4 +/- 1.3 kcal/mol through a series of multireference configuration interaction (MR-CI) calculations that systematically expand the orbital basis set. The estimated value of DELTAH(f)degrees suggests that HSO may well be involved in a catalytic cycle that depletes ozone in the atmosphere. In contrast to all earlier theoretical studies, the computed energy difference between the HSO and SOH isomers is estimated to be 5.4 kcal/mol, with the HSO isomer being more stable.