The Interplay of Angle Strain and Aromaticity: Molecular and Electronic Structures of [0 n ]Paracyclophanes

Abstract

The belt-like polyphenylenes, [0n]paracyclophanes, (n = 5 and 6), were studied using semi-empirical, ab initio and DFT methods. The mol. structure, rotational barrier on twisting a single Ph ring and the arom. character within each ring as well as in the whole mol. were evaluated. [05]Paracyclophane is predicted to have a quinonoid structure. But the equatorial pentaphenyl fragment found in C70 as well as the hexagons of the less strained [06]paracyclophane have benzenoid character. Approx. band structures were derived for larger cycles of [0n] paracyclophanes. [on SciFinder(R)]