Abstract :
The CH3O+CO → CH3+CO2 reaction is studied by ab initio molecular orbital calculations. The potential energy surface of the reaction system is examined with second-order Møller–Plesset perturbation theory (MP2) and the quadratic configuration interaction (QCISD) method. The QCISD(T) method is used to compute the energetics. It is found that the reaction proceeds through a CH3OCO intermediate. This intermediate is predicted to be stable and its heat formation is estimated as −37.3±3 kcal mol−1. The best estimate of the heat of reaction is −38.0 kcal mol−1 at the QCISD(T)/6-311++G(3df, 3pd)//QCISD/6-311G(2d, 2p) level of theory. At the same level of theory, the barrier height for addition is 5.8 kcal mol−1. However, the dissociation of the CH3OCO intermediate into CH3+CO2 is found to be the rate-limiting step. The dissociation barrier is estimated as 38.2 kcal mol−1. The CH3O+CO reaction shows several features that are similar to the OH+CO reaction.
