A non-symmetrical compartmental ligand derived from acetazolamide and its mononuclear cobalt(III) complex with an empty outer compartment

The Schiff base, non-symmetrical, compartmental ligand N-[5-(2-{[2-hydroxy-3-methoxy-phenyl-methylidene]-amino}-phenyl-sulfamoyl)-[1,3,4]thiadiazol-2-yl]-acetamide (H3L) has been prepared by condensation of the acetazolamide derivative N-[5-(2-amino-phenylsulfamoyl)-[1,3,4]thiadiazol-2-yl]-acetamide (3) with 2-hydroxy-3-methoxy-benzaldehyde. The complexation of H3L with cobalt(II) chloride in pyridine under aerobic conditions yielded [CoIII(HL)(py)2][CoII(py)Cl3] · CH3CH2OH (4). The single crystal X-ray structures of H3L and 4 are reported. In the mononuclear cation [CoIII(HL)(py)2]+ of 4 the octahedral cobalt(III) ion is bound at the inner, metal ion binding site, and the larger, empty, outer metal binding site is partly occupied by the hydrogen-bonded ethanol molecule of crystallisation.