The reaction of aluminum atoms with methane

Abinitio SCF and CISD calculations with split valence and larger basis sets have been carried out for several possible reactions of ground state ( 2 P) aluminum atoms with methane. In particular, the barriers to insertion of Al into a CH bond to give a CH 3 AlH intermediate and the abstraction of a hydrogen by Al to give AlH and CH 3 have been studied. At the SCF level, transition state structures have been located and verified by vibrational analyses. In addition, intrinsic reaction coordinates (IRC) have been followed from the transition state geometries down to reactants and to products. Calculated vibrational frequencies and lowest excitation energy for the CH 3 AlH intermediate are in good agreement with matrix isolation experimental results. As anticipated on the basis of MO natural correlation symmetry arguments, the energy barrier to the insertion reaction is high (~50 kcal mol −1 at the CI level). The energy requirement for the abstraction reaction is similar.[Formula: see text]