Computational studies on CH/? interactions

Abstract

Intermolecular interactions in CH/π systems have been studied by PCILO and ab initio MO methods to elucidate the origin of the attractive interactions. In the PCILO calculations, the van der Waals molecules of CH₄+ C₂H_n(n= 2 or 4) were more stable than that of CH₄+ C₂H₆, and the most stable arrangement was such that the carbon atom in methane is shifted from the C₂ axis perpendicular to the C–C–H plane of ethene. Ab initio MO results supported this conclusion and showed also that the main contributions to attractive CH/π interactions come from electrostatic and charge-transfer effects. These results were supported by electrostatic-potential maps of C₂H₄ and C₂H₆.