THEORETICAL-STUDIES ON MECHANISMS OF THE INSERTION OF BORON INTO METHANE AND ITS CONSEQUENT REACTIONS

The potential energy surfaces for the insertion of a boron atom into C H4 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) calcula tions using a correlation-consistent atomic natural orbital basis set cc-pVTZ to determine the energetics. The detailed mechanisms leading t o different products are obtained, and the initial insertion reaction is exothermic by 52.6 kcal mol(-1) with a potential barrier of 20.8 kc al mol(-1). The calculations predict that the B+CH4 system maintains C s symmetry in the course of insertion. The stable conformations of the CH3BH molecule are finally formed by an intramolecular rotation. The CH3BH molecule found can isomerize to the planar CH2BH2 molecule with C-2v symmetry through a barrier of 18.8 kcal mol(-1). Production of th e CH2BH molecule is found to involve a complex mechanism: the most lik ely pathway is direct dissociation of the CH3BH molecule into CH2BH an d H atom. The HBCH molecule is formed only by 1,1-H-2 elimination from the CH3BH molecule, while CH3 and BH are produced by the direct abstr action reaction.