【作者】 李瑞延；

【导师】 李志儒；

【作者基本信息】 吉林大学 ， 物理化学， 2005， 博士

【摘要】 使用精确的Counterpoise 优化方法,在MP2 水平得到了系列的氢键、π氢键及π卤键的结构体系。在CCSD(T)水平使用Counterpoise 方法得到了高水平的相互作用能结果,分析和研究了体系结构变化以及氢键和卤键的性质。主要贡献如下: 1. 对不饱和与饱和分子形成的氢键二聚体CH2O-HF、CH2O-H2O 和CH2O-NH3 体系进行了理论研究,研究发现体系形成环形结构是因为体系中存在一个新的π-type 氢键相互作用。π-type 氢键弯曲了体系的σ-type 氢键,导致二聚体的环形结构形成。2. 在C2H4-HF 、C2H3F-HF 、g-C2H2F2-HF 、cis-C2H2F2-HF 和trans-C2H2F2-HF 五个π氢键体系的研究中,分析并总结了F 取代效应对π氢键体系结构和π氢键性质的影响。F 取代效应延长了π氢键,在C2H3F-HF、g-C2H2F2-HF 和cis-C2H2F2-HF 三个体系中,π氢键还进一步发生了偏移或倾斜。研究发现,上面三个体系中也存在着π-type 氢键,π-type 氢键使π氢键发生了弯曲。F 取代效应降低了体系的相互作用能,增大了相互作用能中电子相关贡献。3. π卤键C2H4-nFn-ClF (n=0-2) 与π氢键体系的F 取代效应基本类似。但在MP2/aug-cc-pVDZ 水平,使用高精度的CP(counterpoise)优化几何的方法,而得到的C2H4-ClF、C2H3F-ClF、g-C2H2F2-ClF、trans-C2H2F2-ClF 和cis-C2H2F2-ClF 五个二聚体的稳定结构与π氢键体系相比,有下面五个特点:(1).体系的π卤键具有较长的键长(比π氢键体系约长0.5?);(2).具有更大的电子相关效应(比π氢键体系大2-3 倍);更多还原

【Abstract】 (1) The optimized structures of CH2O-HF, CH2O-H2O, CH2O-NH3, and CH2O-CH4.with all real frequencies were obtained by the MP2 level and four basis bets (6-311G(d,p), 6-31+G(d,p), 6-311++G(2d,2p), and 6-311++G(3df,3pd). The structures of CH2O-HF, CH2O-H2O, and CH2O-NH3 are cycle-shaped. This is because there is a larger bend of their σhydrogen bonds O???H-Y (Y= F, O, N). The results show that the larger bend of σhydrogen bond is caused by a secondary weak interaction. The secondary weak interaction is named π-type hydrogen bond in this paper, and The bend of σ-type H-bond O???H-Y (Y= F, O, N) is illustrated and interpreted by the attractive interaction of a chemically intuitive π-type hydrogen bond. The π-type hydrogen bond is the interaction between one of the H atoms of CH2O and lone pair(s) on the F atom in HF, the O atom in H2O, or the N atom in NH3. By contrast with π-type hydrogen bond in dimers saturated molecule, the π-type hydrogen bond is a new type in π-type hydrogen bond. For CH2O-CH4, because there is not a π-type hydrogen-bond to bend its linear hydrogen bond, the structure of CH2O-CH4 is a non-cyclic shaped. The interaction energy of hydrogen bonds and the π-type H-bond are calculated and discussed at the CCSD(T) /6-311++G(3df,3pd) level. (2) By the counterpoise-correlated potential energy surface method (interaction energy optimization), five structures of C2H4-nFn?HF (n=0, 1, 2) dimers with all real frequencies have been obtained at MP2/aug-cc-pVDZ level. The structure and π-Hydrogen bond of dimer has been changed by the influence of F substituent effect, obviously. By contrast with the π-Hydrogen bond of C2H4-HF, the π-Hydrogen bonds of C2H4-nFn?HF (n=1, 2) are elongated by F substituent effect. For C2H3F-HF, g-C2H2F2-HF, cis-C2H2F2-HF, the π-Hydrogen bonds are further deformed. These changes (elongate, shift and deformation) of π-Hydrogen bond mainly come from deformation of π-electron cloud of C=C bond. The densities of π-electron cloud have deviated or shifted slightly from the molecular vertical plane passing through C=C bond, so the π-Hydrogen bond is also sloped or shifted. The π-Hydrogen bond of C2H3F-HF, g-C2H2F2-HF, and cis-C2H2F2-HF are bent by the π-type H-bond in the dimers. The F substituent effect added the electron correlation contribution of interaction energy. Intermolecular interaction energies of the dimers are calculated to be -3.9 for C2H4-HF, -2.8 for C2H3F-HF, -2.1 for g-C2H2F2-HF, -1.6 for cis-C2H2F2-HF, -1.3 kcal/mol for trans-C2H2F2-HF, at CCSD (T)/aug-cc-pVDZ level. (3) The dimers C2H4-nFn-ClF (n=0, 1, 2) are proper model as investigating of π-halogen bond kind in the paper. Using the counterpoise-correlated potential energy surface method (interaction energy optimization), the C2V, C2, C1, Cs and Cs stationary structures of the更多还原