Half‐Wave Potentials of 1‐AZA‐ and 1,8‐Diazaanthraquinones

The redox properties of a series of 1-azaanthracene-9,10-diones, 1,8-diazaanthracene-9,10-diones, 1,8-diazaanthracene-(1H)2,9,10-triones and 1,8-diazaanthracene-(1H, 8H)2,7,9,10-tetraones have been studied. The results obtained show that the 2-pyridone moiety is a stronger electron acceptor than the pyridine ring, in agreement with reactivity data. 1-Hydroxy-1-azaanthracene-2,9,10-triones, synthesized from 1-azaanthracene-9,10-dione-N-oxides, show redox properties close to 1,8-diazaanthracene-2,7,9,10-tetraones, and therefore the cyclic hydroxamic acid unit behaves also as an strong electron acceptor. Voltammetric half-wave first potentials correlate with the energies of the LUMO in model compounds.