Ls. Nichols et Aj. Illies, Experimental and theoretical investigation into the structural and thermodynamic properties of the mixed methyl halide association radical cations, INT J MASS, 187, 1999, pp. 413-424
An experimental and theoretical study of the ion/molecule association react
ions of methyl halide radical cations with mixed methyl halides (X, Y = I,
Br, Cl, F) has been carried out. MS/MS unimolecular and collision-induced d
issociation experiments were performed on the association products and prov
ide strong evidence for formation of a two-center three-electron (2c-3e) bo
nded structure, [CH3X therefore YCH3](.+), for all association products exc
luding [C2H6FCl](.+). The [C2H6FCl](.+) results suggest the following atomi
c connectivity for this association product: [CH2Cl-H-FCH3](.+). Two metast
able fragmentation pathways were observed for [CH3I therefore BrCH3](.+) an
d [CH3Br therefore ClCH3](.+): direct cleavage of the 2c-3e bond and elimin
ation of a methyl group. Only direct cleavage was observed in [CH3I therefo
re ClCH3](.+), [CH3I therefore FCH3](.+), and [CH3Br therefore FCH3](.+). K
inetic energy release distributions were measured and unimolecular kinetic
modeling studies were performed on the metastable reaction pathways. Unimol
ecular kinetic modeling was carried out using phase space calculations and
molecular parameters from density functional theory (DFT) calculations. DFT
was also used to investigate the potential energy surfaces for each system
. (C) 1999 Elsevier Science B.V.