二聚体HX-ClF(X=F,Cl,Br)的结构及其双卤键X…Cl性质的理论研究

The Theoretic Study of The Structure and Di-halogen Bond Properties for Dimers HX-ClF (X=F,Cl,Br)

使用从头计算方法,以二聚体HX-ClF(X=F,Cl,Br)作为卤键的摸型进行了研究.几何优化计算使用了高精度的CP(counterpoise)修正的分子间势能面(PES)方法,在MP2/6-311++G(3df,3pd)水平,得到了二聚体HX-ClF,(X=F,Cl,Br)的三个稳定结构.在三个二聚体HF-ClF,HCl-ClF和HBr-ClF的结构中存在着两种分子间相互作用——双卤键X…Cl和氢键H…Cl.二聚体HX-ClF的X…Cl键长顺序是:2.758(HF-ClF)<3.145(HCl-ClF)<3.212(HBr-ClF),它们的H…Cl键长分别是3.301(HF-ClF)、3.471(HCl-ClF)和3.554(HBr-ClF).用高水平的CCSD(T)/6-311++G(3df,3pd)计算的相互作用能分别是:-2.15kcal/mol(HF-ClF)、-1.54kcal/mol(HCl-ClF)和-1.64kcal/mol(HBr-ClF).计算结果表明,相互作用能的电子相关效应是重要的.由于相互作用能的电子相关效应随着电子给予体原子F、Cl、Br的顺序增大,从而,二聚体HBr-ClF的X…Cl相互作用能也相应地被增大.

<Abstrcat>With the ab initio,the halogen bond X…Cl model of the dimers HX-ClF,(X=F,Cl,Br) have been studied. Using the high accurate counterpoise-corrected potential energy surface method (interaction energy optimization),the Cs symmetrical stationary structures of dimers HX-ClF,(X=F,Cl,Br) with all real frequencies have been obtained at the MP2/6-311++G(3df,3pd)level.In the structure of dimers HF-ClF,HCl-ClF,and HBr-ClF,there are two kinds of intermolecular weak interaction di-halogen bond X…Cl and hydrogen bond H…Cl.The X…Cl length order of dimers HX-ClF is 2.758? for HF-ClF<3.145? for HCl-ClF<(3.212)? for HBr-ClF,and the hydrogen bond H…Cl length order is 3.301? for HF-ClF<3.471? for HCl-ClF<3.554? for HBr-ClF.The calculated interaction energies with high accurate CCSD(T)/6-311++G(3df,3pd) level are,-2.15 kcal/mol for HF-ClF respectively,1.54 kcal/mol for HCl-ClF and -1.64 kcal/mol for HBr-ClF.The calculated results show that the electric correlative effects of interaction energy are important.Because the electric correlative effect of interaction energy is increased with the order of electric donor ability of F,Cl,Br increasing.Thus,the interaction energies of X…Cl of dimer HBr-ClF is also increased,correspondingly.