The mixed-ligand complexes are prepared by the reaction of thiobarbituric acid with five-coordinate Co(II), Ni(II) and Cu(II) of arylideneanthranilie acids. The so obtained complexes are characterised by elemental analyses, electronic and IR spectroscopy, X-ray powder diffraction patterns, and conductivity measurements. It is found that thiobarbituric acid coordinates as a neutral or mono-basic mono-dentate ligand to form carboxylate-bridged five-coordinate mixed-ligand complexes. Both the ligands and mixed-ligand complexes have been tested for their antimicrobial activities.

Four coordinate Ni(II) and Cu(II) chelates formed by reaction of two azopyrazolone derivatives with metal sulfate, acetate, or nitrate are described. It is concluded that the ligands possess tautomeric equilibria and can coordinate to the metal ion as neutral or monobasic bidentates. The so-obtained complexes are characterized by elemental and thermal analyses, IR and electronic spectra, as well as conductivity measurements. A pseudo-tetrahedral polymeric structure is proposed for all the complexes in which the acetate, nitrate, or sulfate is attached to the metal ion in the bridging bidentate mode. It is observed that the chelates formed are more potent as antimicrobial agents than the free ligands.

Four coordinate Ni(II) and Cu(II) chelates formed by reaction of two azopyrazolone derivatives with metal sulfate, acetate, or nitrate are described. It is concluded that the ligands possess tautomeric equilibria and can coordinate to the metal ion as neutral or monobasic bidentates. The so-obtained complexes are characterized by elemental and thermal analyses, IR and electronic spectra, as well as conductivity measurements. A pseudo-tetrahedral polymeric structure is proposed for all the complexes in which the acetate, nitrate, or sulfate is attached to the metal ion in the bridging bidentate mode. It is observed that the chelates formed are more potent as antimicrobial agents than the free ligands.

Twelve new complexes of Cu(II), Ni(II), Co(II) and Cd(II) with 5-phenyl, 5-p-tolyl and 5-aminothioacetimide-azo-8-hydroxyquinoline have been synthesized. The ligands act as bidentate (NO) chelating agents forming the bis-chelate complexes. Analytical, conductivity, spectral and thermal data are consistent with six coordinated structure in the case of Cu(II), Ni(II), Co(II) and four coordinate structure in the case of the analogues Cd(II). It is identified that the metal chelates possess enhanced antibacterial and antifungal activities relative to the free ligands