4-Hydroxy-ONN-azoxybenzene

The oxidation of 4-hydroxyazobenzene provided a mixture of two azoxy compou nds, which were separated by column chromatography. The isomer with the hig her melting point appeared to belong to the alpha (ONN) series, as determin ed by X-ray diffraction. The molecule, C12H10N2O2, is almost planar. The be nzene rings are twisted by 11.7 (2) (substituted) and 4.1 (1)degrees (unsub stituted) with respect to the ONN plane. The molecules are connected to one another by strong O-H ... O hydrogen bonds forming chains extended along [ 001], which are bound by much weaker C-H ... O hydrogen bonds forming layer s in the bc plane.