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首页> 外文期刊>Chemistry: A European journal >Analysis of why boron avoids sp ~2 hybridization and classical structures in the B _nH _(n+2) series
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Analysis of why boron avoids sp ~2 hybridization and classical structures in the B _nH _(n+2) series

机译：为何硼避免B〜nH _（n + 2）系列中的sp〜2杂化和经典结构

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We performed global minimum searches for the B _nH _(n+2) (n=2-5) series and found that classical structures composed of 2c-2e B-H and B-B bonds become progressively less stable along the series. Relative energies increase from 2.9 kcal mol ~(-1) in B _2H _4 to 62.3 kcal mol ~(-1) in B _5H _7. We believe this occurs because boron atoms in the studied molecules are trying to avoid sp ~2 hybridization and trigonal structure at the boron atoms, as in that case one 2p-AO is empty, which is highly unfavorable. This affinity of boron to have some electron density on all 2p-AOs and avoiding having one 2p-AO empty is a main reason why classical structures are not the most stable configurations and why multicenter bonding is so important for the studied boron-hydride clusters as well as for pure boron clusters and boron compounds in general. Classical structures composed of 2c-2e B-H and B-B bonds become progressively less stable along the series B _nH _(n+2) (n=2-5). Relative energies increase from 2.9 kcal mol ~(-1) in B _2H _4 to 62.3 kcal mol ~(-1) in B _5H _7. It is believed that this occurs because boron atoms in the studied molecules tend to avoid sp ~2 hybridization and trigonal structures at the boron atoms, as in that case one 2p-AO is empty, and thus highly unfavorable (see figure).
机译：我们对B _nH _（n + 2）（n = 2-5）系列进行了全局最小搜索，发现由2c-2e B-H和B-B键组成的经典结构沿该系列逐渐变得不稳定。相对能量从B _2H _4中的2.9 kcal mol〜（-1）增加到B _5H _7中的62.3 kcal mol〜（-1）。我们认为这是因为被研究分子中的硼原子试图避免sp〜2杂交和硼原子处的三角结构，因为在这种情况下一个2p-AO为空，这是非常不利的。硼在所有2p-AO上具有一定电子密度并且避免2p-AO空的这种亲和力是主要原因，经典结构不是最稳定的构型，并且多中心键对于研究的硼氢化物簇如此重要以及一般的纯硼团簇和硼化合物。由2c-2e B-H和B-B键组成的经典结构沿B _nH _（n + 2）系列（n = 2-5）逐渐变得不稳定。相对能量从B _2H _4中的2.9 kcal mol〜（-1）增加到B _5H _7中的62.3 kcal mol〜（-1）。认为发生这种情况是因为所研究的分子中的硼原子倾向于避免sp〜2杂交和硼原子处的三角结构，因为在这种情况下，一个2p-AO是空的，因此非常不利（见图）。

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