<i>ab initio</i>分子軌道法による弱い分子間相互作用の解析

Abstract

In this article the author summarizes analysis of intermolecular interactions (π/π interactions of benzene, naphthalene, thiophene dimers and benzene-perfluorobenzene cluster, CH/π interactions of benzene clusters with methane, ethylene, acetylene and chloroform, cation/π inteactions of benzene clusters with alkali and alkaline metal cations and N-alkylpyridinium cation, halogen bonds of halobenzene and pentafluorohalobenzene with pyridine and hydrogen bond coorperativity in water-crownophane complex) by high-level ab initio calculations. The ab initio calculations provide detailed information on the interactions (magnitude of attraction, directionality, origin of attraction). The dispersion interaction is the major source of the attraction in the π/π and CH/π interactions. The electrostatic and induction interactions are responsible for the strong attraction in cation/π interactions. The electrostatic interaction is the origin of the attraction and strong directionality of halogen bonds. The basis set and electron correlation effects on the calculated interaction energies are discussed. Although the structure of CH/π interactions is similar to π hydrogen bonds, the nature of CH/π interactions is completely different from hydrogen bonds, which shows that it is sometimes misleading to discuss the nature of the interactions based solely on the structural information.