Directionality of intermolecular C–F···F–C interactions in crystals: experimental and theoretical charge density study

Bonding intermolecular F···F interactions were analyzed in crystal of a fluorinated benzene derivative using topological analysis of experimental charge density distribution. It was found that the values of electron density and potential energy density in bond critical points of the F···F interactions in crystal depended on the distance between the fluorine atoms, rather than on the corresponding C–F···F angles. The directionality of these F···F interactions was demonstrated by DFT-D and MP2 calculations for model hexafluorobenzene dimers. Possible discrepancies between dimerization energies computed by ab initio methods and via empirical correlations are discussed.