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本文采用密度泛函理论B3LYP方法在6-31G(d)水平上,用Gaussian03程序对1-乙基-3-甲基咪唑四氟硼酸盐离子液体进行了理论计算,几何优化得到两种旋光异构体,通过计算得到电荷分布、热力学参数、振动频率以及分子轨道参数,对优化结构的电荷特性、热力学性质、振动特性、分子轨道进行了综合分析。结果发现有一部分电荷从阴离子转移到阳离子,阴阳离子间共形成了5对氢键,使阴阳离子间的静电作用减弱,这是导致离子液体熔沸点低的一个重要原因;咪唑环上与甲基相连的N原子与甲基上H原子也有相互作用,此作用会影响到阴阳离子间的静电作用与氢键作用的强弱变化趋势,并且红外吸收比较强的C-H键都参与了氢键的形成。
In this paper, density functional theory B3LYP method at the level of 6-31G (d), Gaussian03 program for 1-ethyl-3-methylimidazolium tetrafluoroborate ionic liquid theoretical calculations, the geometry optimization of the two kinds of optical rotation By calculating the charge distribution, thermodynamic parameters, vibrational frequencies and molecular orbital parameters, the charge, thermodynamic, vibration and molecular orbitals of the optimized structure were comprehensively analyzed. As a result, it was found that a part of the charges transferred from the anion to the cation. Five pairs of hydrogen bonds were formed between the anion and the cation, which reduced the electrostatic interaction between the anion and the cation. This is one of the important reasons for the low melting point of the ionic liquid. The connected N atom also interacts with the H atom on the methyl group. This effect will affect the electrostatic interaction between the anion and the cation and the strength and weakness of hydrogen bonding, and the CH bonds with strong IR absorption are involved in the formation of hydrogen bonds .