A negligible antiaromatic destabilization is found in planar D4h 1,3,5,7-cyclooctatetraene with alternating bond lengths. The same is also true for the delocalized D8h structure, which has a stabilization energy of only 3-4 kcal mol-1 . According to quantum-chemical calculations, the ground state of 1 is expected to be the planar C2v -symmetric (1,1) singlet diradical 1'.
Keywords: antiaromaticity; cyclooctatetraene; diradicals; resonance energy.
© 2001 WILEY-VCH Verlag GmbH, Weinheim, Fed. Rep. of Germany.