CALCULATION OF KINETIC-PARAMETERS OF THE REACTION DISSOCIATIVE ELECTROCHEMICAL REDUCTION OF HALOMETHANES IN POLAR-SOLVENT

The kinetics of dissociative reduction reactions of methyl halides in polar solvents, e(-) + CH(3)X --> CH3. + X(-), is considered in the framework of previously developed theory. The potential energies of the reactants and products are described by the Morse and exponential curves as functions of the C-X distance. The parameters of the Morse potential are taken from experiment, and those for the exponential function are obtained from quantum-chemical calculations of radical anions CH(3)X(.-) by the PM3 method. The solvent reorganization energy is calculated with the use of the real charge distribution on CH(3)X and CH(3)X(.-) in terms of the ellipsoidal model. Theoretical values of the rate constant are compared with experimental data at Delta F = 0. The agreement is good for X = Cl and Br but is poor for X = I. The latter is attributed to bad values of quantum-chemical parameters of the PM3 method for I.