Resumen de Electron Structure of Arx′ZnZnArx′ (Arx′ = C6H3-2, 6-(C6H5)2) Determined from ELF and NBO Data: Effects of Hydrogen/Sodium Atoms on Zn–Zn Interactions
Xiaoyan Li, Jie Sun, Zheng Sun, Yanli Zeng, Shijun Zheng, Lingpeng Meng
The nature of Zn–Zn bonding in Arx′ZnZnArx′ (Arx′ = C6H3-2,6-(C6H5)2)) was studied and was compared with the bonding in its derivatives Arx′Zn(μ-H)2ZnArx′, Arx′Zn(μ-H)(μ-Na)ZnArx′, and Arx′Zn(μ-Na)2ZnArx′; this study was carried out within the framework of the atoms in molecules (AIM) theory and using electron localization function (ELF) and natural bond orbital (NBO) analysis. The calculated results showed that, in Arx′ZnZnArx′, the Zn–Zn bond was stronger than a single bond; it was intermediate between a single and a double bond. Howerver, this bond was different from the classical single bond, in which the valence basin is concentrated tightly around the bond axis; in this case, the valence basin was in a toroidal configuration around the Zn–Zn bond, with axial symmetry. The Zn–Zn bond was weakened and its axial symmetry broken down when one or two hydrogen/sodium atoms were introduced to Arx′ZnZnArx′; the influence of a hydrogen atom was more pronounced than that of a sodium atom. It was shown that two Zn–H–Zn or Zn–Na–Zn three-center–two-electron (3c-2e) bridged bonds existed in Arx′Zn(μ-H)2ZnArx′, Arx′Zn(μ-H)(μ-Na)ZnArx′, and Arx′Zn(μ-Na)2ZnArx′. In the formation processes of these 3c-2e bridged bonds, the sodium atom acted as the electron donor, whereas the hydrogen atom acted as an electron acceptor.
