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

The dynamics of the dissociation of the benzyl chloride radical anion to a benzyl radical and chloride anion was studied theoretically. To this end tw o different conformations of benzyl chloride were examined: one featuring a 90 degrees 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 (c onformation 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 th e dynamics of this process was obtained using the dynamic reaction coordina te (DRC) algorithm for tracing reaction paths. The DRC method shows a quali tative 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 doe s not. (C) 2001 Elsevier Science B.V. All rights reserved.