Density functional theory computational study of the four-centered elimination CH2OH+ → CHO+ + H2 reaction

Abstract

The reactant, transition state, and product of the CH 2 OH + → CHO + + H 2 reaction were computed with HF, QCISD(T), G1, G2, and G2MP2 ab initio methods as well as with 21 density functional theory (DFT) methods. In all calculations the large 6-311++G(3df,3pd) basis set was used. With the same theory models, the activation barrier and heat of reaction was estimated. On the basis of geometry, intrinsic reaction coordinate (IRC) calculations support that the reaction is a concerted 1,2-elimination and proceeds through a product-like transition state structure. It was determined that HF and QCISD(T) methods have the problem of correctly computing the energy reaction profile. On the contrary, B3LYP, B3PW91, BPW91, and BVWN for reactant's geometries reproduce experimental results quite well.