title: Reaction cross sections and thermal rate constant for Cl(-) + CH3Br → ClCH3 + Br(-) from J-dependent quantum scattering calculations.
abstract: Employing dimensionality-reduced time-independent quantum scattering theory and summation over all possible total angular momentum states, initial-state selected reaction cross sections for the exothermic gas-phase bimolecular nucleophilic substitution (SN2) reaction Cl(-) + CH3Br → ClCH3 + Br(-) have been calculated. The carbon-halogen bonds and the rotation of the methyl halides are taken into account. In agreement with previous calculations for J = 0, initial rotational motion of CH3Br decreases the reaction probability and consequently the cross sections. The experimentally obtained thermal rate constant for 300 K is reproduced within the experimental error. For lower temperatures, it is calculated to be below the experimental values but shows the same strong increase for T → 0.
authors.affiliation: Institut für Physikalische Chemie, Universität Göttingen, Tammannstr. 6, D-37077 Göttingen, Germany. sschmat@gwdg.de.
authors.forename: Carsten
authors.initials: C
authors.lastname: Hennig
authors.affiliation: Institut für Physikalische Chemie, Universität Göttingen, Tammannstr. 6, D-37077 Göttingen, Germany. sschmat@gwdg.de.
authors.forename: Stefan
authors.initials: S
authors.lastname: Schmatz