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用ab initio和MNDO两种方法,对CH_3NO_2沿C-N键断裂的热解反应过程进行了较细致的计算研究。所得势能曲线(E-R_(C-N))彼此一致,并与Kaufman等的近期结果相符。将各单点下所得正则离域MO进行了定域化处理,发现当C和N原子间的距离R_(C-N)=1.6-1.8A时,定域成键σ_(C-N)-MO从能级较低的第5个占有MO跃升为HOMO(即第16个MO)。考察占有和未占有前沿轨道能级和位相,可推断在CH_3NO_2热解的初始阶段,通过分子重排形成C-O键的可能性较小。其热解引发步骤可能是生成·CH_3和·NO_2双自由基。
Using ab initio and MNDO methods, the pyrolysis reaction process of CH_3NO_2 cleavage along C-N bonds has been studied in detail. The resulting potential energy curve (E-R_ (C-N)) is in agreement with each other, consistent with recent results by Kaufman et al. Localization of the regular delocalized MOs obtained at each single point shows that when the distance between CN and N atoms is 1.6-1.8A, the localized bond σ_ (CN) -MO shifts from the level The lower fifth occupancy MO jumped to HOMO (the 16th MO). Examining the possession and unoccupied frontier orbital energy levels and phases, it is inferred that there is less likelihood of forming C-O bonds by molecular rearrangements in the initial stages of pyrolysis of CH 3 NO 2. The pyrolysis initiation step may be to generate · CH_3 and · NO_2 diradicals.