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为进一步了解卤键的作用本质,在MP2(full)/6-311++G(d,p)水平上,采用Gaussian 03量子化学软件包、AIM2000程序和电子密度拓扑分析程序GTA 2000,从理论上研究H_2CX…F_2,(CH_2)_2X…F_2(X=O,S)分子间卤键复合物的结构和性质,计算和分析复合物的几何构型、分子间相互作用能、化学键的电子密度拓扑性质等。研究表明,H_2CX,(CH_2)_2X(X=O,S)与F_2间存在键鞍点,卤键的形成方向正好是O原子(或S原子)的电子密度浓集区伸展的方向;分子间卤键的形成伴随着F-F键键长的增加、振动频率的红移及电子密度拓扑性质的改变,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;而且H_2CS,(CH_2)_2S与F_2间作用强于H_2CO,(CH_2)_2O与F_2间的作用。
To further understand the nature of the halogen bond, Gaussian 03 quantum chemistry software package, AIM2000 program and electron density topological analysis program GTA 2000 were used at the level of MP2 (full) / 6-311 ++ G (d, p) The structure and properties of H 2 CX ... F_2, (CH_2) _2X ... F_2 (X = O, S) intermolecular halogen bond complexes were studied. The geometrical configurations, intermolecular interaction energies, electronic density of chemical bonds Topology and so on. The results show that the bond-forming point between H_2CX, (CH_2) _2X (X = O, S) and F_2 exists in the direction of the electron density concentration region of O atom (or S atom) With the increase of FF bond length, the red shift of vibration frequency and the topological property of electron density, the halogen bond in the complex is between the covalent bond and ionic bond, and the electrostatic interaction is dominant. Moreover, the interaction between H_2CS, (CH_2) _2S and F_2 is stronger than that of H_2CO, (CH_2) __2O and F_2.