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MP2/6-311+G**//B3LYP/6-311+G**理论水平上,对二甲基亚砜(DMSO)中强碱催化N-(2-卤基苯基)-N’-苯基乙脒分子内氮芳基化合成苯并咪唑反应机理及反应性做了理论研究.研究结果显示:标题反应的反应机理并不是Bolm等提出的自由基机理或分步的S_NAr机理,而是只有一个过渡态的协同S_NAr机理.几何结构宽松度分析和自然集居数分析(NPA)都不能解释标题反应的反应性大小顺序问题.多参数拟合揭示标题反应的反应能垒主要由最高占据轨道能EHOMO或亲核原子N10的区域亲核性指标ω-N10控制,另一因素为亲核原子N10所带负电荷多少.而被进攻的C2原子所带电荷以及几何结构宽松度L%对反应能垒几乎没有影响.方法对比研究发现,MP2/6-311+G**//B3LYP/6-311+G**方法所得结果与实验结果吻合较好,能更好地描述标题反应的相对能量和反应性顺序.
MP2 / 6-311 + G ** // B3LYP / 6-311 + G ** At a theoretical level, the strong base in dimethylsulfoxide (DMSO) catalyzes the reaction of N- (2-halophenyl) -phenylacetamidine, the theoretical and experimental studies on the reaction mechanism and reactivity of benzimidazole have been carried out.The results show that the reaction mechanism of the title reaction is not the free radical mechanism or stepwise S_NAr mechanism proposed by Bolm et al. But only a transition state of the synergistic S_NAr mechanism.Geometry looseness analysis and natural population aggregation (NPA) can not explain the order of magnitude of the reactivity of the title reaction.Multiple parameter fitting reveal that the reaction barrier of the title reaction is mainly composed of The highest occupancy orbit nucleus EHOMO or nucleophilic nucleus N10 nucleophilic indicators ω-N10 control, the other factor is the nucleophilic atom N10 with a negative charge, while attacked by the C2 atom charge and the geometric structure of the loose degree L % Has almost no effect on the energy barrier of the reaction.METHODS The results of MP2 / 6-311 + G ** / B3LYP / 6-311 + G ** method are in good agreement with the experimental results and can better describe the title The relative energy of the reaction and the order of reactivity.