PROTONATED METHANESULFONIC-ACID AND RELATED IONS - A STUDY OF THEIR GAS-PHASE STRUCTURE AND REACTIVITY

[CH3SO2]+, [CH3SO3H2]+ and [CH3SO2OCH3H]+, positive even-electron ions from hexavalent sulfur compounds, have been studied by Fourier transform ion cyclotron resonance and collision-induced dissociation (CID). These ions showed no evidence of undergoing S + O methyl group shift, at variance with easy skeletal rearrangements frequently postulated for ionized sulfones and sulfonyl derivatives. A proton affinity value of 184 +/- 2 kcal mol 1 has been obtained for methanesulfonic acid by the bracketing procedure, but the site of proton attachment in [CH3SO3H2]1 ions could not be established, either by CID or kinetic evidence. The methylation of SO2 by (CH3)2F+ ions has been ascertained to yield [CH3SO2]+ ions methylated on oxygen, in analogy to the same reaction observed in a superacid medium.