Department of Chemistry and Biochemistry, Utah State University, 0300 Old Main Hill, Logan, Utah 84322-0300, USA.
J Chem Phys. 2011 Sep 14;135(10):104301. doi: 10.1063/1.3625959.
The structures and the electronic properties of two aluminum-doped boron clusters, AlB(7)(-) and AlB(8)(-), were investigated using photoelectron spectroscopy and ab initio calculations. The photoelectron spectra of AlB(7)(-) and AlB(8)(-) are both broad, suggesting significant geometry changes between the ground states of the anions and the neutrals. Unbiased global minimum searches were carried out and the calculated vertical electron detachment energies were used to compare with the experimental data. We found that the Al atom does not simply replace a B atom in the parent B(8)(-) and B(9)(-) planar clusters in AlB(7)(-) and AlB(8)(-). Instead, the global minima of the two doped-clusters are of umbrella shapes, featuring an Al atom interacting ionically with a hexagonal and heptagonal pyramidal B(7) (C(6v)) and B(8) (C(7v)) fragment, respectively. These unique umbrella-type structures are understood on the basis of the special stability of the quasi-planar B(7)(3-) and planar B(8)(2-) molecular wheels derived from double aromaticity.
采用光电光谱法和从头算方法研究了两种掺铝硼团簇 AlB(7)(-)和 AlB(8)(-)的结构和电子性质。AlB(7)(-)和 AlB(8)(-)的光电子能谱都很宽，表明阴离子和中性体之间的基态之间存在显著的几何变化。进行了无偏全局最小搜索，并将计算出的垂直电子离解能与实验数据进行了比较。我们发现，Al 原子并没有简单地取代 AlB(7)(-)和 AlB(8)(-)中母体 B(8)(-)和 B(9)(-)平面团簇中的 B 原子。相反，这两个掺杂团簇的全局最小值呈伞状，分别具有一个 Al 原子与六元和七元金字塔形的 B(7)(C(6v))和 B(8)(C(7v))片段离子相互作用。这些独特的伞状结构是基于准平面 B(7)(3-)和平面 B(8)(2-)双芳香性衍生的分子轮的特殊稳定性来理解的。
