THEORETICAL STUDY ON THE MECHANISM OF THE CH3OH + •XH3 (X = C, Si) REACTIONS ☆

The mechanism for the reactions of methanol (CH3OH) with •XH3 (X = C, Si) radicals have been investigated by ab initio molecular orbital theory based on the CCSD(T)//B3LYP/aug-cc-pVTZ method. For the CH3OH + •CH3 reaction, the major product pathways channels are H-abstraction forming PR1 (CH3O• +CH4: 0,0 kcal.mol-1) and PR2 (•CH2OH + CH4: -8,1 kcal.mol-1) via transition states TS1 and TS2 lying 12,0 and 12,8 kcal/mol above the reactants, respectively. While for the CH3OH + •SiH3 reaction, the major product pathways channels are the H-abstraction forming PR7 (•CH2OH + SiH4: 3,4 kcal/mol) and substitution channels forming PR8 (H• + CH3OSiH3: -0,3 kcal.mol-1) and PR9 (•CH3 + SiH3OH: -28,7 kcal.mol-1) via transition states TS7 (16,2 kcal.mol-1), TS8 (16,5 kcal.mol-1) and TS9 (17,0 kcal.mol-1), respectively. The predicted geometry parameters for the species in the PESs and the heats of reaction in this work are in good agreement with available experimental data.