Theoretical studies on mechanisms of the insertion of boron into methane and its consequent reactions

Abstract

The potential energy surfaces for the insertion of a boron atom into CH4 and its consequent processes have been characterized employing MP2 and QCISD methods with the 6-311G(d,p) and 6-311 + + G(d,p) basis sets in order to locate the stationary points, followed by QCISD(T) calculations using a correlation-consistent atomic natural orbital basis set cc-pVTZ to determine the energetics. The detailed mechanisms leading to different products are obtained, and the initial insertion reaction is exothermic by 52.6 kcal mol−1 with a potential barrier of 20.8 kcal mol−1. The calculations predict that the B + CH4 system maintains Cs symmetry in the course of insertion. The stable conformations of the CH3BH molecule are finally formed by an intramolecular rotation. The CH2BH2 molecule found can isomerize to the planar CH2BH2 molecule with C2v symmetry through a barrier of 18.8 kcal mol−1. Production of the CH2BH molecule is found to involve a complex mechanism: the most likely pathway is direct dissociation of the CH3BH molecule into CH2BH and H atom. The HBCH molecule is formed only by 1,1-H2 elimination from the CH2BH molecule, while CH and BH are produced by the direct abstraction reaction.