科研之友
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摘要
The properties of inorganic benzenes have been investigated by means of second-order MollerPlesset perturbation theory (MP2) calculations and quantum theory of atoms in molecules (QTAIM) studies. In this work, the sigma and pi electron densities were separated from the total electron densities, and it was therefore possible to evaluate the contributions of sigma and pi electrons to the chemical bonds and properties of inorganic benzenes. The following conclusions are given: (1) The pi-attractors positions correlate to their respective atomic radii. With increasing atomic number in the same period, the attractor of pi-electron densities becomes closer to its respective nucleus. With increasing atomic number in the main group, the position of the p attractor becomes farther from its respective nucleus. (2) The strength of the chemical bonds of the inorganic benzene rings is determined by sigma-electron densities, not pi-electron densities; their bonding character is mainly determined by the sigma-electron density; however, the role of the pi-electron density cannot be neglected. (3) For the inorganic benzenes studied, the electron localization function for pi (ELF pi) values are related to the differences of the electronegativity between the neighboring atoms of the inorganic benzene rings, Delta chi(X,Y). The smaller the difference of Delta chi(X,Y), the higher the value of ELF pi, resulting in more aromatic properties of the inorganic benzenes.
