OCS,CO_2,N_2O与烯、炔烃之间π…π作用的电子密度拓扑研究

Topological Studies on the π…π Interactions between OCS,CO_2,N_2O and Hydrocarbon

采用MP2/aug-cc-pVDZ方法对氧硫化碳(OCS)、二氧化碳(CO2)、一氧化二氮(N2O)与乙烯(C2H4)、乙炔(C2H2)、2-丁炔(C4H6)之间形成的平行构型复合物中的分子间相互作用进行了理论研究.复合物的相互作用能按照B…C2H4<B…C2H2<B…C4H6(B=OCS,CO2,N2O)的顺序依次增大,相互作用距离按照B…C2H4>B…C2H2>B…C4H6(B=OCS,CO2,N2O)的顺序依次减小.采用电子密度拓扑分析理论方法,讨论了复合物中π…π作用的成键特性.电子密度拓扑分析表明复合物中形成了弱的分子间相互作用,且以静电作用为主;π电子密度分子图与全电子密度分子图中键径方向是一致的,说明π…π作用在本文所讨论的体系中起着很重要的作用.NBO分析表明净电荷迁移从电子给体C2H4,C2H2,C4H6到电子受体OCS,CO2,N2O,迁移数按照B…C2H4<B…C2H2<B…C4H6(B=OCS,CO2,N2O)的顺序依次增大,与相互作用能的顺序一致.

The parallel-shaped complexes OCS…hydrocarbon,CO2…hydrocarbon,and N2O…hydrocarbon（hydrocarbon=ethylene,acetylene,dimethylacetylene） were investigated at the MP2/aug-cc-pVDZ level.The interaction energies are along the sequence of B…C2H4B…C2H2B…C4H6（B=OCS,CO2,N2O）,and the interaction distances are in sequence of B…C2H4B…C2H2B…C4H6（B=OCS,CO2,N2O）.The π…π interactions were investigated by using the topological analysis of electron density.The nature of interactions of the parallel-shaped complexes belongs to weak electrostatic interactions.The bond paths in the molecular graphs of π electron density and total electron density show the same orientation,indicating that the π…π interactions play an important role in these intermolecular interac-tions.NBO analyses showed that charge transfers were observed from C2H4,C2H2,C4H6 to OCS,CO2,N2O,and the amount of charge transfer are in sequence of B…C2H4B…C2H2B…C4H6（B=OCS,CO2,N2O）,which exactly match the order of the interaction energies.