XH···HOCl···YH体系中氢键与卤键协同效应的理论研究

A theoretical study of cooperativity between hydrogen bond and halogen bond in XH···HOCl···YH complexes

采用MP2方法在6-311++G(d,p)基组水平上对三分子体系XH…HOCl…YH(X=F,Cl,Br,OH;Y=F,Cl,Br,OH,NH2)中氢键和卤键之间的协同效应进行了研究。研究过程中计算了二体XH…HOCl中氢键,二体HOCl…YH中卤键和三体XH…HOCl…YH中氢键和卤键的键长、分子间的相互作用能以及它们的振动频率。发现和二体相比,三体中氢键和卤键的键长缩短,分子间的相互作用能增大,振动频率增大。再通过AIM分析,比较了二体、三体中氢键和卤键键鞍点处电子密度强弱的变化,结果电子密度在三体中明显增大,分析结果还显示氢键和卤键属于分子间弱相互作用的范畴,它们的静电作用和二体相比也有所增强。这些现象都表明三体中氢键和卤键之间存在正的协同效应。

This paper aims at studing the cooperativity between hydrogen bond and halogen bond in XH···HOCl···Y（ X = F,Cl,Br,OH; Y = F,Cl,Br,OH,NH2） complexes by using the MP2 method and 6-311 ＋ ＋ G（ d,p） basis set. During the study,the bond lengths,intermolecular interaction energies and vibration frequencies were calculated in XH···HOCl,HOCl···YH and XH···HOCl···YH complexes.The result shows that when compared with XH···HOCl,HOCl···YH systems,the XH···HOCl···YH complexs has shorter bond lengths but greater intermolecular interaction energies and higher vibration frequencys. Through AIM analysis and a comparison of the change of the electron density at the bond critical points between the two complexes,the results show that the electron density have obvious increase in the XH···HOCl···YH complexes.Besides,the results also show that all the bonds belong to the weak interactions and they have stronger electrostatic interaction compared with XH···HOC1 and HOCl···YH complexes. All these above analysis indicate that cooperativity exists between hydrogen bond and halogen bond in XH···HOCl···YH complexes.