AbstractThe aromatic1H‐ and13C‐NMR. spectra of some metal complexes of o, o′‐dihydroxyazobenzenes are shown to be useful in distinguishing the two possible isomers (acolar and discolar) stemming from the non equivalence of the two ligating azo nitrogen atoms. The ortho aromatic carbon atoms, C(6) and C(12) experience relatively large upfield shifts between 12.8 and 15.7 ppm when the adjacent nitrogen atom is coordinated. The protons attached to these carbon atoms are shifted downfield. The valuesnJ(15N,13C) for the ligand 2,2′‐dihydroxy‐3‐methyl‐4′‐chloro‐5‐(t‐butyl)