S–H bond dissociation enthalpies: The importance of a complete basis set approach

The S–H homolytic bond dissociation enthalpies (BDEs) for several compounds of reference were estimated by different theoretical methods including CCSD(T), CBS-QB3, and the multi-coefficient extrapolated density functional theory multi-level approaches, MCG3-MPWB and MCG3-TS. Emphasis was placed on the importance of extrapolating theoretical BDEs to complete basis set. A very good agreement between S–H BDEs from CCSD(T) calculations and experiment is observed when a simple dual extrapolation scheme to complete basis set proposed by Truhlar is adopted. For thiophenol, our CCSD(T) estimate for the S–H BDE (347.2 kJ mol−1) supports a recent experimental value obtained from time-resolved photoacoustic calorimetry (349 ± 5 kJ mol−1).