Huckel-like rule of superaromaticity for charged paracyclophanes

Paracyclophanes, in which four or more benzene units are linked at the 1,4-positions by ethylene bridges, show annulene characteristics upon charging. It was proved that a Huckel-like rule of superaromaticity holds for molecular ions of these species. Here superaromaticity represents energetic stabilization due to cyclic motion of pi-electrons along the macrocycle. If this type of paracyclophane molecule or any of its closed-shell molecular ions is super-antiaromatic, it will probably become superaromatic either by acquiring two more pi-electrons or by losing two pi-electrons. (C) 2003 Elsevier B.V. All rights reserved.