Metal complexes of antibiotic drugs. Studies on dicluxacillin complexes of FeII, FeIII, CoII NiII and CuII.

The synthesis and characterization of dicluxacillin (DC) complexes with di- and tri-valent metal ions are described. The nature of bonding of the chelated DC and its metal complexes structures have been elucidated on the basis of their spectroscopic (infrared, solid reflectance, magnetic spectra, mass and thermal analysis) properties. In all the complexes studied, the DC acts as a chelate monoanionic ligand with coordination involving the carboxylate O atom and the endocyclic N of the thiazole ring. The DC ligand forms mono-ligand complexes of the general formula [M(DC)(H2O)x(A)]. yH2O where DC is the uninegatively charged bidentate ligand and A = OAc in case of CuII and Cl in case of FeIII, FeII, CoII and NiII ions. IR, solid reflectance spectra and magnetic moment measurement are used to infer the structure and to illustrate the coordinating capacity of the ligand. From the thermal decomposition curves, the water molecules of crystallization are removed in a single stage while the decomposition of the ligand and coordinated water molecules occur in the second and subsequent stages. Different thermodynamic kinetic parameters namely activation energy (E*), enthalpy of activation (AH*), entropy of activation (AS*) and free energy change of activation (AG*) are calculated using Coats and Redfern equation.