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在MP2/6-311+g**水平上优化了(CH3)2Cl+的几何构型,得到的构型参数与实验吻合得很好.相同理论水平下对该阳离子的异构化机理进行了探讨,该反应的决速步需翻越250.6kJ·mol-1的势垒,在C-Cl键断裂及H迁移的协同作用下,可生成质子化的氯乙烷(CH3CH2ClH)+,如有其他阴离子存在,可失去一个质子而转变为氯乙烷.另外,利用自然键轨道理论(NBO)对鎓离子(CH3)2Cl+和碳硼烷阴离子(CHB11Cl11)-相互作用的本质进行了详细探讨,阴阳离子之间的二级稳定化能表明,阴离子上的Cl原子孤对电子与鎓离子上C-H反键相互作用较大,拉长了鎓离子上非平面的C-H键.阴阳离子的静电势图进一步证实负静电势主要分布在氯代碳硼烷上,正电势主要分布在二甲基氯鎓离子上.在B3LYP/6-31G的水平上计算了甲基正离子在鎓离子和碳硼烷阴离子上的迁移机理,迁移过程只需克服11.3kJ·mol-1能垒即可,说明当碳硼烷阴离子存在时,二甲基氯鎓离子不可能发生异构化反应得到氯乙烷,只能产生氯仿.
The geometrical configuration of (CH3) 2Cl + was optimized at the level of MP2 / 6-311 + g **, and the configuration parameters obtained were in good agreement with the experimental data. The isomerization mechanism of the cation was also discussed under the same theoretical level , The rate step of the reaction needs to climb over the potential barrier of 250.6 kJ · mol-1. Under the synergistic action of C-Cl bond cleavage and H migration, protonated chloroethane (CH3CH2ClH) + can be generated. If other anions , Which can lose a proton and change into chloroethane.In addition, the nature of the interaction between onium ion (CH 3) 2 Cl + and carborane anion (CHB 11 Cl 11) is discussed in detail by using the theory of natural bond orbital (NBO) The second-order stabilization shows that the lone pairs of Cl atoms on the anion have a large interaction with the CH antibonding on the onium ion, which elongates the non-planar CH bond on the onium ion. The electrostatic potential diagrams of the anions and cations further confirm The negative electrostatic potential is mainly distributed in the chlorocarbon borane, the positive potential is mainly distributed in the dimethylchloronium ion.Consideration of the methylcations on the onium ion and the carborane anion at the B3LYP / 6-31G level Migration mechanism only need to overcome the 11.3kJ · mol-1 energy barrier, indicating that when the carborane anion When the child is present, dimethyl chloride ion isomerization reaction to give ethyl chloride impossible, can only produce chloroform.