Enthalpy of formation of CH3SO and CH3SO2: A difficult case in quantum chemistry

Abstract

The enthalpies of formation of CH3SO and CH3SO2 at 298.15 K were determined at a high level of electronic correlation, CCSD(T), and with the use of Woon and Dunning's procedure to reach the complete basis set limit. This study led to values of-16.7 kcal mol-1 and -53.1 kcal mol-1, respectively, for CH3SO and CH3SO2, which are expected to be the most accurate ones to date. Analysis of existing calculations at various levels of theory clearly shows the need of large basis sets and a high level of electronic correlation treatment to produce reliable and accurate results.