Quantum chemical study of C-SH bond dissociation energies for some thiol compounds

In this paper, quantum chemical calculations are used to estimate the C-SH bond distances and bond dissociation energies (BDEs) for 16 thiol compounds. Since DFT methods have been researched to have low basis sets sensitivity for small and medium molecules in our earlier work [Jun Zhao, Xinlu Cheng, Xiangdong Yang, J. Mol. Struct. (Theochem) 766 (2006) 87], these compounds are studied by employing the hybrid density functional theory (B3LYP, B3PW91, B3P86, PBE1PBE) and the complete basis set (CBS-Q) method together with the 6-311G** basis set. By comparing the obtained results with the available experimental results, we find that CBS-Q and B3P86 methods calculated results agree very well with the experimental values, with the average absolute errors of 1.6 and 3.7 kcal/mol, respectively. So considering the expensive computational time, CBS-Q method can be chosen as a satisfactory method of predicting the accurate BDEs for removal of the SH group in small and medium size thiol compounds. And B3P86 method may give reliable BDEs for larger thiol molecules we haven't studied.