The importance of quadrupolar interactions in determining the structure of solid hydrocarbon–fluorocarbon compounds

Calculations of the contributions of quadrupole–quadrupole interactions to the intermolecular potentials of the molecular pairs benzene–benzene, hexafluorobenzene–hexafluorobenzene, and benzene–hexafluorobenzene have shown that, in complete agreement with X-ray structural data, the preferred orientation in the two pure solids is that in which neighbouring molecules are perpendicularly oriented whereas the molecules in the solid mixture are predicted to adopt a parallel, face-to-face configuration.