The enthalpy of formation of the HSO radical revisited

The enthalpy of formation of the HSO and SOH radicals has been determined employing the CCSD(T) methodology with the aug-cc-pV(X+d)Z basis sets X = D,T,Q,5. Our best estimations are Δ H f , 298 0 ( HSO ) = - 5.2 ± 0.5 and Δ H f , 298 0 ( SOH ) = - 1.6 ± 0.5 kcal / mol . The procedure employed to determine those values involves, extrapolation to the CBS limit, a correction for core-valence and relativistic effects. This result is in reasonable agreement with our previous estimations [Int. J. Quant. Chem. 80 (2000) 439] −6.6 and −1.6 kcal/mol for HSO and SOH, respectively. However, it is larger than the lower bound recently estimated by Balucani et al. [JPC. 120 (2004) 9571] −3.0 kcal/mol at 0 K (−3.7 kcal/mol at 298 K).