Charged paracyclophanes behave as annulenes with enhanced anisotropy

Paracyclophanes, in which benzene units are linked at the 1,4 positions by ethylene bridges (1-4), show annulene characteristics upon charging. The de pendence of the magnetic properties of these charged rigid systems on the n umber of pi-electrons in the peripheries has been studied systematically. F or the first time it can be shown that upon extensive reduction, two observ able diatropic anionic stages exist (for 3). The results of advanced DFT ca lculations are in line with the experimental results. The limit on the number of pi-electrons in the periphery of annulenes, whic h still exhibit aromatic or anti-aromatic behavior, is extended far beyond the number of 26.