AB-INITIO STUDY OF THE ABSTRACTION REACTIONS OF CF3O

The hydrogen atom abstraction reactions of CF3O from CH4, C2H6, and H2O have been studied using the 6-31G(*) basis set including correlation to the MP4(FC)SDTQ level. In a few instances the 6-31G(**) and the 6.31++G(**) basis sets were employed. CF3O forms prereaction adducts with CH4, C2H6, and H2O with binding energies of 1.46, 1.08, and 4.25 kcal/mol, respectively, at the MP4 levels. The transition states for CH4, C2H6. and H2O were found to be 5.06, -0.03, and 7.07 kcal/mol above the reactants, respectively, at the MP4 levels. CF3OH was found to form postreaction adducts with CH3, C2H5 and OH with binding energies of 2.58, 4.48, and 7.38 kcal/mol, respectively. The overall energy changes for the reaction of CF3O with CH4, C2H6, and H2O are -7.79, -10.74 and -2.54 kcal/mol, respectively, at the MP4 level. The calculated transition state energies are in reasonable agreement with experimental results for C2H6 and H2O but somewhat higher for CH4. Geometries are presented for the prereaction adduct, the transitions states, and the postreaction adduct and discussed. The implications of these results in relevant experiments and in the atmosphere are discussed.