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运用量子化学微扰理论MP2方法,采用6-311++G(d,p)基组,对吡咯与双卤分子XY(XY=ClF BrF,BrCl)形成的卤键复合物进行构型全优化,得到各分子的稳定几何构型和分子间相互作用能。利用电子密度拓扑分析方法分析卤键复合物的拓扑性质,探讨了该类分子间卤键的作用本质。证明吡咯与双卤分子间存在Y—X…N和Y—X…π2类相互作用,且后者比前者强。复合物中的卤键介于共价键与离子键之间,偏于静电作用成分为主。形成卤键后,2种类型卤键复合物中的电子受体X—Y键伸长,其振动频率发生红移。用电子密度拓扑分析程序GTA-2000,将π型卤键体系中π电子与σ电子分开处理,绘制出π电子密度等值线图和Laplacian量等值线图,更加形象地说明π型卤键的存在和作用本质。利用AIM程序计算了卤键复合物中各原子电子积分的性质,原子积分性质随着卤键形成发生了改变。
Using the MP2 method of quantum chemical perturbation theory, the configuration of halohalide complex formed by XY (XY = ClF BrF, BrCl) pyrrole and bishalide was optimized by 6-311 ++ G (d, p) , Get the stable geometry of each molecule and the intermolecular interaction energy. The topological properties of halogen bond complexes were analyzed by electron density topological analysis, and the nature of the halogen bond between these molecules was discussed. It is proved that there exist Y-X ... N and Y-X ... π2 interactions between the pyrrole and the bishalide molecules, and the latter is stronger than the former. The halogen bond in the complex is between the covalent bond and the ionic bond, which is mainly the electrostatic interaction component. After the halogen bond is formed, the X-Y bond of the electron acceptor in the two types of halogen bond complexes is elongated, and the vibrational frequency is red-shifted. Using electron density topological analysis program GTA-2000, the π electron and the σ electron in the π-type halogen bond system are treated separately, the π electron density contour map and the Laplacian volume contour map are drawn, and the π-type halogen bond The existence and role of essence. Using the AIM program, we have calculated the integral of each electron in the halogen bond complex. The integral property of the atom changes with the formation of the halogen bond.