Wang Weizhou, Hobza Pavel
Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic and Center for Biomolecules and Complex Molecular Systems, Flemingovo nAm. 2, 166 10 Prague 6, Czech Republic.
J Phys Chem A. 2008 May 1;112(17):4114-9. doi: 10.1021/jp710992h. Epub 2008 Mar 18.
The origin of the X-Hal bond-length change in the halogen bond of the X-Hal...Y type has been investigated at the MP2(full)/6-311++G(d,p) level of theory using a natural bond orbital analysis, atoms in molecules procedure, and electrostatic potential fitting methods. Our results have clearly shown that various theories explaining the nature of the hydrogen bond cannot be applied to explain the origin of the X-Hal bond-length change in the halogen bond. We provide a new explanation for this change. The elongation of the X-Hal bond length is caused by the electron-density transfer to the X-Hal sigma* antibonding orbital. For the blue-shifting halogen bond, the electron-density transfer to the X-Hal sigma* antibonding orbital is only of minor importance; it is the electrostatic attractive interaction that causes the X-Hal bond contraction.
利用自然键轨道分析、分子中的原子方法和静电势拟合方法，在MP2（全）/6 - 311++G（d，p）理论水平上研究了X-Hal...Y型卤键中X-Hal键长变化的起源。我们的结果清楚地表明，各种解释氢键本质的理论都不能用于解释卤键中X-Hal键长变化的起源。我们对此变化提供了一种新的解释。X-Hal键长的伸长是由电子密度转移到X-Hal σ反键轨道引起的。对于蓝移卤键，电子密度转移到X-Hal σ反键轨道的作用较小；是静电吸引相互作用导致了X-Hal键的收缩。
