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应用半经验的AM1和密度泛函B3LYP/6-31G*方法对1,3-丁二烯与C59XH(X=N,B)Diels-Alder环加成反应的区域选择性进行理论研究,选择一些有代表性的C59XH(X=N,B)的6—6键探讨环加成反应的机理.1,3-丁二烯与C59NH进行的Diels-Alder反应,随着加成位置远离C59NH的N原子,活化能越来越低,但都比1,3-丁二烯与C60相应反应的活化能高.与此相反,对于1,3-丁二烯与C59BH进行的环加成反应,加成位置最靠近B原子的2,12/r-和2,12/f-过渡态的势垒最低,并且比1,3-丁二烯与C60进行环加成反应的活化能约低18kJ·mol-1,其产物也是热力学最稳定的.与C60相应的反应相比,C59NH和C59BH中N和B原子不同的电子性质对其邻位双键进行Diels-Alder环加成反应的活性产生了不同影响,前者使反应活性降低,后者使反应活性增强.
The semi-empirical AM1 and B3LYP / 6-31G * methods were used to study the regioselectivity of 1,3-butadiene and C59XH (X = N, B) Diels-Alder cycloaddition reactions. A representative C59XH (X = N, B) 6-6 bond mechanism of the cycloaddition reaction.1,3-Butadiene and C59NH Diels-Alder reaction, with the addition position away from the C59NH N Atomic, the activation energy is getting lower and lower, but higher than the activation energy of 1,3-butadiene and C60 corresponding reaction. In contrast, for 1,3-butadiene and C59BH cycloaddition reaction plus The 2,12 / r- and 2,12 / f-transition states with the closest position to the B atom have the lowest potential barrier, and the activation energy of cycloaddition reaction with 1,3-butadiene and C60 is about 18 kJ · mol-1, the product is also thermodynamically the most stable.Compared with the corresponding reaction of C60, C59NH and C59BH N and B atoms of different electronic properties of its adjacent double bond Diels-Alder cycloaddition reaction activity generated Different effects, the former reduced reactivity, the latter increased reactivity.