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用密度泛函B3LYP方法研究了过渡金属钐类卡宾与乙烯的环丙烷化反应的机理.对钐类卡宾试剂CH3SmCH2I和CH2CH2反应的反应物、中间体、过渡态和产物构型的全部结构几何参数进行了优化,并计算了THF溶液的溶剂化效应,用内禀反应坐标(IRC)计算和频率分析方法,对过渡态进行了验证.结果表明:CH3SmCH2I与CH2CH2环丙烷化反应按亚甲基转移机理(通道A)和卡宾金属化机理(通道B)都可以进行,与锂类卡宾的反应机理相同,通道A比通道B反应的势垒降低了14.65kJ/mol.溶剂化效应使通道B比通道A的反应势垒大幅度提高,更有利于反应沿通道A进行,而不利于通道B.
The mechanism of cyclopropanation of transition metal samarium carbene with ethylene was studied by means of density functional theory B3LYP method.All structural geometrical parameters of reactants, intermediates, transition states and product configurations of samarium carbene reagent CH3SmCH2I and CH2CH2 The solvation effect of THF solution was calculated and the transition state was verified by IRC and frequency analysis.The results showed that the cyclopropanation reaction of CH3SmCH2I with CH2CH2 was carried out by methylene transfer The mechanism (channel A) and the carbene metallization mechanism (channel B) are both the same as the reaction mechanism of lithium carbene, and the potential barrier of channel A is 14.65kJ / mol lower than that of channel B. The solvation effect makes channel B ratio The reaction barrier of channel A is greatly increased, which is more favorable for the reaction to proceed along channel A, which is unfavorable to channel B.