title: Ion-molecule reactions of [C, H(3), S](+) ions and evidence for long-lived triplet CH(3)S(+).
abstract: Gas-phase [C, H(3), S](+) ions obtained by electron impact from (CH(3))(2)S at 14 eV undergo two distinct low-pressure ion-molecule reactions with the parent neutral: proton transfer and charge exchange. The kinetics of these reactions studied by Fourier transform ion cyclotron resonance (FT-ICR) techniques clearly suggests the [C, H(3), S](+) species to be a mixture of isomeric ions. While proton transfer is consistent with reagent ions displaying the CH(2)SH(+) connectivity, the observed charge exchange strongly argues for the presence of thiomethoxy cations, CH(3)S(+), predicted to be stable only in the triplet state. Charge exchange reactions are also observed in the reaction of these same [C, H(3), S](+) ions with benzene, toluene and phenetole. For these substrates, the CH(2)SH(+) ions can promote proton transfer and electrophilic methylene insertion in the aromatic ring with elimination of H(2)S. The results obtained for the different substrates suggest that the fraction of long-lived fraction of thiomethoxy cations obtained at 14 eV by electron ionization of dimethyl sulfide amounts to ~(22 -/+ 4)% of the [C, H(3), S](+) fragments.
authors.affiliation: Universidad Nacional de Córdoba, Facultad de Ciencias Químicas, INFIQC, RA-5000 Córdoba, Argentina.
authors.forename: Mariano
authors.initials: M
authors.lastname: Teruel
authors.forename: Patricia R P
authors.initials: PR
authors.lastname: de Moraes
authors.forename: Luciano A
authors.initials: LA
authors.lastname: Xavier
authors.forename: José M
authors.initials: JM
authors.lastname: Riveros