Does ionized dimethylsulfoxide produce O-protonated sulfine CH2SOH+at threshold? A quantum chemical investigation

The heats of formation of O- and C-protonated sulfine, CH2SOH+ and CH3-SO+, have been assessed by ab initio molecular orbital calculations executed at the MR-SDCI//CASSCF/DZPP+f(S) level of theory as 739 and 838 kJmol, respectively, using the experimentally known dissociation limits CH+3+SO· · and CH3.+ SO+ as anchors. These results confirm our earlier proposal that the measured heat of formation (736 ± 8 kJmol) of the mz 63 ions, [H3, C, O, S]++ generated from dimethylsulfoxide, CH3-S(O)-CH3, corresponds to CH2SOH+, and not to CH3-SO+.