Aromaticity and Through-Space Interaction between Aromatic Rings in [2.2]Paracyclophanes

The HOMA index calculated for [2.2]­paracyclophanes in the solid state reveals a slight decrease of aromaticity. Interactions between aromatic rings of [2.2]­paracyclophane have been investigated using AIM and NCI analysis in both crystal and optimized [2.2]­paracyclophane structures. AIM analysis showed that the C···C bond path between the two aromatic rings is present only in few [2.2]­paracyclophanes. The NCI approach visualized the dispersion and repulsive interactions between the aromatic rings of every [2.2]­paracyclophane. Combination of AIM and the NCI approach is necessary for determining and identifying nonbonded interactions in [2.2]­paracyclophanes.