Theoretical Study of the C−F/π Interaction: Attractive Interaction between Fluorinated Alkane and an Electron-Deficient π-System

A molecular interaction between a methane/fluoromethane molecule and a benzene/hexafluorobenzene molecule
was theoretically studied. Attractive interaction between the fluorine atom of the fluoromethane and the
π-system of the hexafluorobenzene was observed (C−F/πF interaction, −2.43 kcal/mol in MP2/aug-cc-pVDZ).
The attractive C−F/πF interaction energy was larger than that of the interaction between methane and benzene
(C−H/πH interaction, −1.47kcal/mol). On the other hand, the very weak repulsive interaction was observed
between the fluorine atom of the fluoromethane and the benzene (C−F/πH interaction, +0.12 kcal/mol). The
interaction energies between methane and benzene (C−H/πH interaction, −1.47 kcal/mol) and between methane
and hexafluorobenzene (C−H/πF interaction, −1.36 kcal/mol) were almost the same.