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‐(1 H )2,9,10‐triones and 1,8‐diazaanthracene‐(1 H , 8 H )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.