关键词: 氧化镁, 甲烷, 化学键, 活化, 分子轨道理论

The reaction of CH_4 + MgO → Mg + CH_3OH has been studied on a singlet state potential energy curve at B3LYP/6-311 + G (2d, 2p) level. The reaction path in which the intermediates transfer from one to another via transition states has been rationalized by their structure, natural bond orbital (NBO) and vibrational frequency analysis. In the first step, the reactants give molecule-molecule complexes OMgCH_4 and MgOCH_4. OMgCH_4 could undergo oxidative addition, cleaving a C-H bond and yielding the insertion product HOMgCH_3. The third step is a reductive elimination, leading to an atom-molecule complex MgCH_3OH, and this step is the rate-determination step in the whole reaction path; the final step is the release of methanol molecule leaving magnesium atom behind. The complex HOMgCH_3 is predicted to be the energetically preferred configuration in the reaction. The overall reaction is exothermic by 146.1 kJ ·mol~(-1).

Key words: MAGNESIUM OXIDE, METHANE, CHEMICAL BONDS, ACTIVATION, MOLECULAR ORBITAL THEORY