全氟取代甲烷二聚体结构的理论研究

Theoretical Study on Structure of Perfluoro Substituted Methanedimer

为全面了解晶体堆积中F...F相互作用的特征及本质,采用MP2/aug-cc-pvdz方法,对四氟甲烷二聚体的能量、结构、F...F作用关键点处的电荷密度拓扑性质及电荷密度转移性质进行了计算。结果表明,四氟甲烷二聚体中,F...F相互作用的距离为2.869A,小于两个F原子的范德华半径之和,表明存在着相互作用;作用角度接近于直线;相互作用强度为较小的负值,证明其结构具有稳定性。键关键点处的电荷密度拓扑性质表明,此作用属于纯闭壳层非共价相互作用。通过非共价相互作用可视化图形,可直观观察二聚体的相互作用,并得到其本质为分子间弱吸引的范德华相互作用。

In order to fully understand the characteristics and nature of F...F interactions in crystal packing, the interaction energy, structure, the topological properties of electrondensity at the critical points of F...F bonds, and charge transfer properties of tetrafluoromethane dimer were studied at the MP2/aug-cc-pvdz level. The results showed that the interaction distance of F...F in the tetrafluoromethane dimer was 2.869A, which was smaller than the sum of the Van der Waals radii of the two F atoms, indicated the existence of interaction. The angle of interaction was close to 180°. The smaller and negative interactionenergy indicated that the structure was stable. The topological properties of electron density at the critical points indicated that this interaction belonged to the pure closed shell noncovalent interaction in nature. The interaction of dimer could be visually observed through non-covalent interactions graph, and the result showed that this interaction was Van der Waals interaction with weak attraction in nature.