Ab initio study of the unimolecular decomposition of 2-butenenitrile: Molecular elimination channels

摘要

Ab initio molecular orbital calculations have been performed for the unimolecular decomposition of 2-butenenitrile (CH3CH=CHCN), especially for HCN and H-2 molecular elimination channels. Structures and energies of the reactants, products, and relevant species in the individual reaction pathways were determined by MP2 gradient optimization and MP4 CCSD(T) single-point energy calculations. Direct 1,1 and 1,2 molecular eliminations and H or CN migration followed by elimination channels were identified. Dissociation rates for the individual reaction pathways were calculated from vibrational frequencies at the ab initio transition state geometries by employing Rice-Ramsperger-Kassel-Marcus theory, from which channel branching ratios were determined. It was concluded that the most important reaction channel should be the direct 1,1 three-center molecular elimination of HCN. (C) 2006 Wiley Periodicals, Inc.