平面五配位硅、 锗XBe5H6(X=Si,Ge)团簇

采用密度泛函理论PBE0方法, 在aug-cc-pVTZ水平上理论预测了含平面五配位硅和锗原子的XBe₅H₆ (X=Si, Ge)团簇. 势能面系统搜索及高精度量化计算表明, 它们均为全局极小结构. XBe₅H₆(X=Si, Ge)团簇整体呈完美的扇形结构: Si/Ge原子被5个金属Be原子配位; 4个H原子以桥基方式与Be原子相键连, 剩余的2个 H原子以端基方式与两端的Be原子成键. 化学键分析表明, XBe₅H₆(X=Si, Ge) 团簇中XBe₅单元具有完全离域的1个π及3个σ键, 外围铍氢间形成4个Be—H—Be 三中心二电子(3c-2e)键及2个定域的Be—H键. XBe₅单元上离域的2π及6σ电子赋予体系π和σ双重芳香性, 并使Si/Ge原子满足八隅律（或八电子规则）. 能量分解-化学价自然轨道分析揭示, Si/Ge和Be₅H₆之间主要为电子共享键.

Planar Pentacoordinate Silicon and Germanium in XBe5H6(X=Si,Ge)Clusters

Computational design of ternary XBe₅H₆（X=Si， Ge） clusters was reported， which were global-minimum structures on the potential energy surfaces， featuring planar pentacoordinate silicon/germanium（ppSi/Ge）. XBe₅H₆ （X=Si， Ge） clusters have the perfect fan-shaped structures： Si/Ge atoms are coordinated by five Be atoms； four H atoms are bonded to Be atoms in bridge mode， and the remaining two H atoms are bonded to Be atoms at both ends. Chemical bonding analyses reveal that the ppSi/Ge core is governed by delocalized 2π/6σ bonding， that is， double π/σ aromaticity， which also makes the Si/Ge atom conform to the octet rule. Additional twelve electrons are contributed to peripheral Be—H—Be and Be—H σ bonding. Energy decomposition analysis-Natural orbital for chemical valence（EDA-NOCV） analyses indicate that there is mainly electron-sharing bonding between the Si/Ge and Be₅H₆ ligands.