An MO-simulation of Elementary Reactions in Hydrocarbon Oxidation. I. A Bimolecular Coupling Reaction of the Methyl Radical and Molecular Oxygen

An MO-simulation of the geometrical change in the bimolecular methane oxidation, CH3+O2→CH3O2, was performed using the CNDO/2 approximation. The geometry of CH3O2 was predicted to take rOO=1.19 Å and ∠COO=111° with fixed distances of rCO=1.44 Å and rCH=1.09 Å. The coupling reaction proceeds smoothly, without any appreciable activation energy, with the geometric transformation of the momentarily-living CH3--O2, with rCO=2.36∼1.44 Å, rOO=1.132∼1.19 Å, and ∠COO=90∼111°. The magnitude of the electron migration between CH3 and O2 throughout the reaction was estimated.