Boron - The Fifth Element
Boron - The Fifth Element
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硼 - 第五元素
DOI：
10.1007/978-3-319-22282-0_2
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发表时间：
2015
期刊：
影响因子：
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通讯作者：
Hnyk D
中科院分区：
文献类型：
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作者：
Hnyk D
本章涉及气相分子结构测定中性硼烷和杂硼烷采用气相电子衍射（GED）和/或现代量子化学计算的技术。这种计算对于计算各种可观测量以便于分析电子衍射数据是有用的。此外，还对两种硫硼烷进行了微波光谱分析（与奥斯陆大学合作）。除非另有说明，否则本章所述工作中使用的样品均来自捷克共和国科学院无机化学研究所，v.v.i.，虽然GED研究主要在爱丁堡大学化学学院进行，但结构特征的硼簇属于结构基序范围，从closotonido，遵守所谓的Wade规则。不遵守韦德规则的硼烷的例子也进行了研究，如所选择的大多面体簇和金属硼烷。最后，为了深入了解电子密度分布，对一些例子进行了实验偶极矩的分析，而早期的硼烷和碳硼烷的GED研究忽略了计算的振动效应，因为这些集群缺乏力场，而目前的硼烷和各种类型的杂硼烷的电子衍射研究使用计算的力场，效果很好。他们揭示了一个有趣的功能：键合和非键合笼距离的振动幅度非常相似，这与各种经验规则不一致，这些规则表明振动幅度应该与相应的核间距离大致成比例。
This chapter deals with gas-phase molecular structure determinations of neutral boranes and heteroboranes employing the techniques of gas-phase electron diffraction (GED) and/or modern quantum chemical calculations. Such calculations were useful for computing various observables in order to facilitate the analysis of the electron diffraction data. Additionally, microwave spectroscopy was utilized for the two thiaboranes (in conjunction with the University of Oslo). Unless otherwise stated, the samples used for the work described throughout this chapter originated from the Institute of Inorganic Chemistry of the Academy of Science of the Czech Republic, v.v.i., Řež while the GED studies were performed mainly in the School of Chemistry at the University of Edinburgh.The structurally characterized boron clusters belong to the range of structural motifs, fromclosotonido, which obey the so-called Wade’s rules. Examples of boranes that do not obey Wade’s rules were also studied, as were selected macropolyhedral clusters and metallaboranes. Finally, in order to gain an insight into electron density distribution, analyses of the experimental dipole moments were carried out for a few examples.Whereas the earlier GED studies of boranes and carbaboranes ignored the calculated vibrational effects because of a lack of force fields for these clusters, the current electron diffraction investigations of boranes and various types of heteroboranes used calculated force fields to good effect. They revealed an interesting feature: the amplitudes of vibration for bonded and non-bonded cage distances are very similar, which is at odds with various empirical rules suggesting that amplitudes of vibration should be roughly proportional to the corresponding internuclear distances.