Abstract or Keywords
Voltammetric and spectroscopic studies of 1,2-acenaphthylenedione, 1, and 1,2-aceanthrylenedione, 2, have shown that the anion radicals of 1 form a pi-dimer whereas a a-dimer is found with 2. The formation of both dimers is seen to be reversible. These conclusions are based on analysis of the cyclic voltammograms and, for the anion radical of 1, the appearance of a long wavelength absorption band at 995 nm as observed by spectroelectrochemical monitoring. Support was also obtained by comparison of the results with those obtained with systems known to form T-dimers (anion radical of 2,3-dichloro-5,6-dicyano-1,4-benzoquinone, 3) and sigma-dimers (anion radical of 9-acetylanthracene, 4). The site of dimerization in the a-dimer of 2 has been assigned through DFT calculations and found to be at a position analogous to that which is known for 4.