Theoretical study of the conformations and strain energies of [n,n]metaparacyclophanes:: Indication of stable edge-to-face and displaced face-to-face conformers for n=4

We have studied [n,n]metaparacyclophanes-model compounds exhibiting edge-to-face and displaced stacked aromatic-aromatic interactions-using semiempirical calculations for n = 2-5 and ab initio calculations for n = 2-4. For n = 2 and 3, the strain energies govern the conformational preference, while for n = 4 and 5 the aromatic-aromatic and strain energies are equally important. The 3,12-dithio[4,4]metaparacyclophanes exhibit edge-to-face aromatic-aromatic intereactions, while the [4,4]metaparacyclophanes and 2,11-dithio[4,4]metaparacyclophanes exhibit displaced stacked aromatic-aromatic interactions.