Yin Bing, Li Teng, Li Jin-Feng, Yu Yang, Li Jian-Li, Wen Zhen-Yi, Jiang Zhen-Yi
MOE Key Laboratory of Synthetic and Natural Functional Molecule Chemistry, Shaanxi Key Laboratory of Physico-Inorganic Chemistry, College of Chemistry and Materials Science, Northwest University, Xi'an 710069, China.
Institute of Modern Physics, Northwest University, Xi'an 710069, China.
J Chem Phys. 2014 Mar 7;140(9):094301. doi: 10.1063/1.4867009.
The first theoretical exploration of superhalogen properties of polynuclear structures based on pseudohalogen ligand is reported here via a case study on eight triply-bridged Mg2(CN)5 clusters. From our high-level ab initio results, all these clusters are superhalogens due to their high vertical electron detachment energies (VDE), of which the largest value is 8.67 eV at coupled-cluster single double triple (CCSD(T)) level. Although outer valence Green's function results are consistent with CCSD(T) in most cases, it overestimates the VDEs of three anions dramatically by more than 1 eV. Therefore, the combined usage of several theoretical methods is important for the accuracy of purely theoretical prediction of superhalogen properties of new structures. Spatial distribution of the extra electron of high-VDE anions here indicates two features: remarkable aggregation on bridging CN units and non-negligible distribution on every CN unit. These two features lower the potential and kinetic energies of the extra electron respectively and thus lead to high VDE. Besides superhalogen properties, the structures, relative stabilities and thermodynamic stabilities with respect to detachment of CN(-1) were also investigated for these anions. The collection of these results indicates that polynuclear structures based on pseudohalogen ligand are promising candidates for new superhalogens with enhanced properties.
本文通过对八个三桥联Mg2(CN)5簇的案例研究，首次报道了基于拟卤素配体的多核结构超卤素性质的理论探索。从我们的高精度从头算结果来看，所有这些簇都是超卤素，因为它们具有较高的垂直电子脱离能（VDE），其中在耦合簇单双三激发（CCSD(T)）水平下的最大值为8.67 eV。尽管在大多数情况下，外层价态格林函数结果与CCSD(T)一致，但它显著高估了三个阴离子的VDE，高估幅度超过1 eV。因此，综合使用多种理论方法对于准确纯理论预测新结构的超卤素性质很重要。这里高VDE阴离子的额外电子的空间分布表明两个特征：在桥联CN单元上有显著聚集以及在每个CN单元上有不可忽略的分布。这两个特征分别降低了额外电子的势能和动能，从而导致高VDE。除了超卤素性质外，还研究了这些阴离子的结构、相对于CN(-1)脱离的相对稳定性和热力学稳定性。这些结果表明，基于拟卤素配体的多核结构有望成为具有增强性质的新型超卤素的候选物。
