A comparison of the chemical bonding and reactivity of Si 8 H 8 O 12 and Ge 8 H 8 O 12 : A theoretical study
A comparison of the chemical bonding and reactivity of Si 8 H 8 O 12 and Ge 8 H 8 O 12 : A theoretical study
复制标题
Si 8 H 8 O 12 和Ge 8 H 8 O 12 化学键和反应性的比较：理论研究
DOI：
10.1063/5.0046059
复制
发表时间：
2021
期刊：
影响因子：
--
通讯作者：
Parish, Carol
中科院分区：
文献类型：
--
作者：
Muya, Jules Tshishimbi;Donald, Kelling J.;Ceulemans, Arnout;Parish, Carol
用从头算量子化学方法和群论方法分析了立方分子八羟基硅氧烷Si8H8O12及其对应物Ge8H8O12的化学键和反应性。采用密度泛函理论和MP2方法结合6-311+ G (d)和6-311++ G （2d, p）基集进行几何优化和振动频率分析。Si8H8O12和Ge8H8O12在Oh对称下是不稳定的，并扭曲成罕见的Th分子对称。根据方法处理的不同，从这种伪姜-泰勒失真中获得的能量范围从0.78到6.14千卡摩尔-1。采用福井函数和分子静电势作为dft的反应性描述符。我们的研究表明Si8H8O12和Ge8H8O12都是硬两性分子。每个笼内的腔是酸性的，能够封装坚硬的小碱基，如F-。笼的外部是碱性的，可以与硬酸形成稳定的外面体配合物，如H+。在Si8H8O12和Ge8H8O12笼中插入f得到了所研究系列中最稳定的内嵌配合物，在CAM-B3LYP/6-311+ G (d)水平上形成能分别为3.50和3.45 eV，在MP2/6-311++ G （d, p）水平上形成能分别为3.61和3.68 eV。计算得到的外面体和内面体配合物的形成能与DFT反应描述符分析一致。
We have analyzed the chemical bonding and reactivity in the cubic molecule octahydridosilsesquioxane, Si8H8O12, and its counterpart Ge8H8O12 by means of ab initio quantum chemical methods and group theory. Density functional theory and MP2 methods combined with the basis sets 6-311+ G (d) and 6-311++ G (2d, p) were used for geometry optimization and vibrational frequency analysis. The geometries of Si8H8O12 and Ge8H8O12 are unstable under Oh symmetry and distort to the rare Th molecular symmetry. The energy gained from this pseudo-Jahn-Teller distortion ranges from 0.78 to 6.14 kcal mol-1 depending on methodological treatment. The Fukui functions and the molecular electrostatic potential were both used as DFT-based reactivity descriptors. Our study shows that Si8H8O12 and Ge8H8O12 are both hard amphoteric molecules. The cavity within each cage is acidic and able to encapsulate hard small bases such as F-. The exterior of the cages is basic and can form stable exohedral complexes with hard acids, as in the case of H+. The insertion of F-in Si8H8O12 and Ge8H8O12 cages gives the most stable endohedral complexes of the series studied, characterized by formation energies of-3.50 and-3.45 eV at CAM-B3LYP/6-311+ G (d) and-3.61 and-3.68 eV at the MP2/6-311++ G (d, p) level, respectively. The calculated formation energies of the exohedral and endohedral complexes align with the DFT reactivity descriptor analysis.