新型超卤素阴离子MX_3^-(M=Be,Mg,Ca;X=F,Cl,Br)的理论研究

Theoretical Study on Novel Superhalogen Anions MX_3^-(M=Be,Mg,Ca;X=F,Cl,Br)

从理论上考察了一种新型超卤素阴离子体系MX_3^-(M=Be,Mg,Ca; X=F,Cl,Br),并对该体系的几何结构、成键特征等性质进行了详细研究。上述MX_3^-的全实频率的几何优化结构在MP2/6-311+G(d)水平下得到并进行自然键轨道(NBO)分析,证实所有的MX_3^-均具有平面几何结构。所研究的MX_3^-表现出相当大的HOMO-LUMO能隙值,说明它们具有很好的稳定性。这些MX_3^-的电离势IP值均高于Cl原子的电子亲和势EA值,因此可以视其为超卤素阴离子。量子化学计算结果表明MX_3^-体系中卤素配体的原子尺寸可以影响其电离势值:配体尺寸越小,电离势值越低。

In this work,a new kind of superhalogen anion MX3^-(M=Be,Mg,Ca;X=F,Cl,Br)was investigated by quantum chemical method.Their structures,bonding features and other properties were discussed in detail.The geometries of these MX3^-with all real frequencies are optimized by MP2method with6-311+G(d)basis set.The natural bond orbital(NBO)analysis is performed at the MP2/6-311+G(d)level.All these MX3^-species present stable planar structure.The stability of the studied MX3^-species is guaranteed by considerable HOMO-LUMO gaps.The ionization potential(IP)of these MX3^-species is higher than the EA of Cl atom,hence they can be considered as superhalogen anions.Quantum chemistry calculation results also reveals that the‘size’of the halogen ligand plays an important role in the IP value:the smaller the halogen ligand,the higher the IP value.