On the dissociation dynamics of the benzyl chloride radical anion. An ab initio dynamic reaction coordinate analysis study

Abstract

The dynamics of the dissociation of the benzyl chloride radical anion to a benzyl radical and chloride anion was studied theoretically. To this end two different conformations of benzyl chloride were examined: one featuring a 90° angle between the Cl–C bond and the aromatic ring (conformation S), the other with the Cl–C bond and the aromatic moiety lying coplanar (conformation E). The potential-energy (PE) surface shows the existence of a conical intersection when studied as a function of the C–Cl bond length and of the rotation angle around the C(sp 2)–C(sp 3) bond. Information on the dynamics of this process was obtained using the dynamic reaction coordinate (DRC) algorithm for tracing reaction paths. The DRC method shows a qualitative difference in the dissociation mechanism of the two conformers. The lifetime of conformation E depends on the amount of kinetic energy assigned to the internal rotational mode motion, whereas that of conformation S does not.