The heat of formation of sulfine, CH2SO, revisited: a CBS-QB3 study

The heat of formation (ΔHf) of sulfine, CH2SO, has been determined by the CBS-QB3 quantum chemical method, using 10 reactions, including the isodesmic reaction CH2SO+SO2→CH2S+SO3. The derived ΔHf of sulfine, −30±6 kJ/mol at 298 K, lies midway between two previously calculated values: −9±14 and −52±10 kJ/mol. The CBS-QB3 derived ΔHf (0 K) was very recently validated against the very accurate Weizmann-1′ (W1′) method [L.N. Heydorn, et al., Z. Phys. Chem. 215 (2001) 141] and there is excellent agreement between the two methods, within 3 kJ/mol. Our recommended value is evaluated against experimental observables, such as the measured proton affinity of CH2SO and the appearance energy of CH2S+OH from dimethyl sulfoxide ions, CH3S(O)CH3+.