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 Co^III(HL)(py)₂]Co^II(py)Cl₃] · CH₃CH₂OH (4). The single crystal X-ray structures of H₃L and 4 are reported. In the mononuclear cation Co^III(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.