Department of Quantum Chemistry, Mendeleev University of Chemical Technology, Miusskaya Square 9, 125047 Moscow, Russia.
J Phys Chem A. 2013 Sep 5;117(35):8459-67. doi: 10.1021/jp405119x. Epub 2013 Aug 23.
The structure, IR harmonic frequencies and intensities of normal vibrations of 20 molecular crystals with the X-Cl···Cl-X contacts of different types, where X = C, Cl, and F and the Cl···Cl distance varying from ~3.0 to ~4.0 Å, are computed using the solid-state DFT method. The obtained crystalline wave functions have been further used to define and describe quantitatively the Cl···Cl interactions via the electron-density features at the Cl···Cl bond critical points. We found that the electron-density at the bond critical point is almost independent of the particular type of the contact or hybridization of the ipso carbon atom. The energy of Cl···Cl interactions, E(int), is evaluated from the linking E(int) and local electronic kinetic energy density at the Cl···Cl bond critical points. E(int) varies from 2 to 12 kJ/mol. The applicability of the geometrical criterion for the detection of the Cl···Cl interactions in crystals with two or more intermolecular Cl···Cl contacts for the unique chlorine atom is not straightforward. The detection of these interactions in such crystals may be done by the quantum-topological analysis of the periodic electron density.
采用固态密度泛函理论方法计算了 20 种具有不同类型 X-Cl···Cl-X 接触（其中 X = C、Cl 和 F，Cl···Cl 距离在 ~3.0 到 ~4.0 Å 之间）的分子晶体的结构、红外谐频和振动强度。通过在 Cl···Cl 键临界点处的电子密度特征，进一步使用所得到的晶体波函数来定量定义和描述 Cl···Cl 相互作用。我们发现，键临界点处的电子密度几乎与接触的特定类型或 ipso 碳原子的杂化无关。Cl···Cl 相互作用的能量 E(int) 是通过 Cl···Cl 键临界点处的连接 E(int) 和局部电子动能密度来评估的。E(int) 变化范围为 2 至 12 kJ/mol。对于具有两个或更多分子间 Cl···Cl 接触的晶体中单个氯原子的 Cl···Cl 相互作用的检测，几何准则的适用性并不直接。可以通过周期性电子密度的量子拓扑分析来检测此类晶体中的这些相互作用。
