Mechanism of hydrogen abstraction from methane and hydrofluoromethanes by hydroxyl radical

The self-consistent charge and configuration method for subsystems (SCCCMS) is applied to discuss the mechanism of hydrogen abstraction from methane and hydrofluoromethanes by hydroxyl radicals. All calculations are done at the B3LYP level of theory with the 6-311G(d,p) basis set. The results of energy partitioning, performed for transition-state structures and two additional points on the minimum energy paths, demonstrate that the perturbation in the external potential (due to nuclei), namely classical/non-classical electrostatic and polarization energies, is the most important. The formation of a pre-reaction molecular adduct is controlled by electrostatic interactions due to their long-range character. The charge-transfer energy is unimportant for the hydrogen abstraction reactions. Copyright (C) 2002 John Wiley Sons, Ltd.