Halogen Bonds in Novel Polyhalogen Monoanions
Halogen Bonds in Novel Polyhalogen Monoanions
复制标题
新型多卤单阴离子中的卤键
DOI：
10.1002/chem.201701116
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发表时间：
2017
期刊：
影响因子：
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通讯作者：
王长崴
中科院分区：
文献类型：
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作者：
王长崴
多卤素一元阴离子[X2 n +1]−（X=Cl和Br;n=1、2、3、4和5）已经使用块局域波函数（BLW）方法进行了系统的研究，该方法提供了价键（VB）分析。对于每一个物种，最稳定的异构体可以被描述为一个中心卤素阴离子X−通过“卤键”非经典地键合到许多二卤素分子X2上。VB分析证实了X−上的孤对电子与X2分子的σ-反键轨道（n→σ*）之间的电荷转移相互作用在X3−和更高类似物中的主导作用。因此，我们的研究表明，这些卤素键基本上是配价共价相互作用。重要的是，[X2 n −1]-和X2之间的电荷转移相互作用随着n的增加而减小，这与刘易斯碱性的减弱（由相应的HOMO能量表征）是雅阁的。电荷转移相互作用的减少强调了[X2 n +1]−中卤键共价的减少。这种趋势突出了多卤素单阴离子中的反合作效应。总而言之，X−和nX 2分子之间的卤键表现出与X−和单个X2分子相同的趋势。换句话说，较大簇中的卤素键与[X3]−阴离子的键合机制相同。因此，不同键长的X− X2卤键形成了整个[X2 n +1]−家族的共价规范。
Polyhalogen monoanions [X2n+1]−(X=Cl and Br;n=1, 2, 3, 4, and 5) have been systematically studied using the block‐localized wave function (BLW) method, which offers a valence bond (VB) analysis. For each species, the most stable isomer can be described as a central halide anion X−non‐classically bonded to a number of dihalogen molecules X2via “halogen bonds”. VB analyses confirm the dominant role of the charge‐transfer interaction between the lone pair on X−and the σ‐anti‐bonding orbital of X2molecule (n→σ*) in X3−and higher analogues. Thus, our study demonstrates that these halogen bonds are essentially dative covalent interactions. Importantly, the charge‐transfer interaction between [X2n−1]−and X2decreases with the increasingn, in accord with the weakening of the Lewis basicity as characterized by the corresponding HOMO energy. The reduction of the charge transfer interaction underscores the reduction of covalence in halogen bonds in [X2n+1]−. This tendency highlights the anti‐cooperative effect in polyhalogen monoanions. All in all, the halogen bond between X−andnX2molecules exhibits the same trends as in X−with a single X2molecule. In other words, halogen bonding in the larger clusters derives from the same bonding mechanism as the [X3]−anion. As such, the X−⋅⋅⋅X2halogen bond at different bond lengths forms a gauge of covalence for the entire [X2n+1]−family.