Li Rui-Yan, Li Zhi-Ru, Wu Di, Li Ying, Chen Wei, Sun Chia-Chung
State Key Laboratory of Theoretical and Computational Chemistry, Institute of Theoretical Chemistry, Jilin University, Changchun 130023, People's Republic of China.
J Chem Phys. 2004 Nov 8;121(18):8775-81. doi: 10.1063/1.1799615.
By the counterpoise-correlated potential energy surface method (interaction energy optimization), five structures of the C(2)H(4-n)F(n)-HF (n = 0,1,2) dimers with all real frequencies have been obtained at MP2/aug-cc-pVDZ level. The influence of F substituent effect on the structure and pi-hydrogen bond of dimer has been discussed. For C(2)H(4-n)F(n)-HF (n = 1,2), the pi-hydrogen bonds are elongated comparing with that for C(2)H(4)-HF. For C(2)H(3)F-HF, g-C(2)H(2)F(2)-HF, cis-C(2)H(2)F(2)-HF, the pi-hydrogen bonds are further deformed. These changes (elongate, shift, and deformation) of pi-hydrogen bond mainly come from deformation of pi-electron cloud of C=C bond. The pi-electron cloud is pushed towards the one C atom, the pi H-bond shift also to the C direction. Since the two lobes of pi-electron cloud have deviated slightly from the molecular vertical plane passing through C=C bond, the pi-hydrogen bond is sloped. Intermolecular interaction energies of the dimers are calculated to be -3.9 for C(2)H(4)-HF, -2.8 for C(2)H(3)F-HF, -2.1 for g-C(2)H(2)F(2)-HF, -1.6 for cis-C(2)H(2)F(2)-HF, -1.3 kcal/mol for trans-C(2)H(2)F(2)-HF, at CCSD(T)/aug-cc-pVDZ level.
通过平衡相关势能面方法（相互作用能优化），在MP2/aug-cc-pVDZ水平上获得了具有所有实频的C(2)H(4-n)F(n)-HF（n = 0,1,2）二聚体的五种结构。讨论了F取代基效应对二聚体结构和π-氢键键的影响。对于C(2)H(4-n)F(n)-HF（n = 1,2），与C(2)H(4)-HF相比，π-氢键被拉长。对于C(2)H(3)F-HF、g-C(2)H(2)F(2)-HF、顺式-C(2)H(2)F(2)-HF，π-氢键进一步变形。π-氢键的这些变化（伸长、位移和变形）主要源于C = C键π电子云的变形。π电子云被推向一个C原子，π氢键也向C方向移动。由于π电子云的两个瓣与穿过C = C键的分子垂直平面略有偏离，π氢键呈倾斜状。在CCSD(T)/aug-cc-pVDZ水平上，计算得到二聚体的分子间相互作用能对于C(2)H(4)-HF为-3.9，对于C(2)H(3)F-HF为-2.8，对于g-C(2)H(2)F(2)-HF为-2.1，对于顺式-C(2)H(2)F(2)-HF为-1.6，对于反式-C(2)H(
