A study of adducts involving dimethyl sulfide radical cations and methyl halides: Experiment, density functional theory, and unimolecular kinetic modeling. 2c-3e bonding vs hydrogen bonding

An experimental study of the ion/molecule association reactions in mixtures of methyl halide and dimethyl sulfide has been performed. MS/MS metastable and collision-induced dissociation experiments were performed on each [C3H 9SX](.+) association product (X = I, Br, Cl, F) in order to determine struc tural conformations and to investigate reaction fragmentation pathways. For X = I, Br, and Cl, a two-center three electron atomic connectivity for the association adduct giving the following structure [CH3X therefore S(CH3)(2 )](+) was observed. For X = F, the data suggests an F-H-S-bonded associatio n adduct, [CH2F-H-S(CH3)(2)](.+). Kinetic energy release distributions were measured for metastable products whenever possible. Furthermore, density f unctional theory and unimolecular kinetic modeling were carried out to furt her probe the potential energy surfaces of these radical cations.