CO_2与HCN、NH_3、H_2O分子络合物的从头计算研究

Ab initio Studies on the Molecular Complexes Between CO2 and HCN, NH3 or H2O

用ab initio能量梯度法(3-21G基组)分别优化CO_2与HCN、NH_3、H_2O_3个分子络合物的平衡几何构型。结果表明HCN、NH_3和H_2O中的N或O原子与CO_2中的C原子之间形成较弱的范德华键,三者的范德华键键长分别为0.2865、0.2775、0.2543nm,稳定化能分别为14.8、27.0、31.2kJ·mol^(-1),3个分子络合物的构型都呈T型,对3个分子络合物的稳定化能的能量分解研究表明它们的形成主要靠静电作用能。

All of the geometries of the title complexes are optimized by the energy gradient technique based on ab initio SCF MO by using 3-21G basis. The results show that the molecular complexes C02-HCN, CO2-NH3, CO2-H2O all have T-shaped equilibrium structures. The van der Waals' bond lengths of the three complexes are 0. 2865, 0. 2775 and 0. 2543 nm, respectively. The binding energies are 14. 8, 27. 0 and 31. 2 kJ/mol, respectively. The results of energy decomposition show that the interaction energy INT is mainly contributed by the electrostatic interaction ES and is slightly by the charge transfer energy CT.