Synthesis and characterization of some metal chelates of schiff base ligands derived from isatin with ethylenediamine and diethylenetriamin

Synthesis and identification of certain metal chelates of nickel [II], cobalt [II], copper [II] and zinc [II] with some Schiff base ligands derived from isatin with ethylenediamine and diethylene triamine have been done. The chemical formulas, mode of bonding and geometrical structures for the investigated metal chelates have been discussed and reported in terms of microchemical analyses, molar conductivities, magnetic measurements, IR and electronic spectra performed for the obtained metal chelates. It has been found that Ni [II] ion coordinates octahedrally with diethylenetriamine bis [isatin] Schiff base ligand, while it possesses square-planar arrangements with the other ligands. The ligands behave as neutral tri-, tetra- and pentadentate towards the central metal ion. Copper [II] ion forms chelates of square-planar structures. Cobalt [II] chelates are suggested to have Oh and Td geometries, whereas Zn [II] ion tetrahedrally coordinates. Electrolytic nature is suggested for chelates

Effect of temperature, medium, metals and ligand structure on the stability of metal complexes of certain schiff base ligands derived frome ninhydrin and isatin with some substituted hyrazines

Stability constants of Ni2+, Co2+, Cd2+, and Mn2+ complexes with some Schiff base ligands of isatin-semi and thiosemicarbazones, isatin S-methylhydrazine carbodithioate and ninhydrinsemi and thiosemi- carbazones have been determined potentiometrically in different media containing ratios of aquo-organic solvents [ethanol, acetone, dioxane, tetrahydrofuran, dimethyl formamide] at ionic strength u=0.04 mol. dm-3 KCl at different temperatures. The acid dissociation constants of the ligands have been also determined under identical conditions. The results obtained are discussed in terms of the molecular structure of the ligands. The solvent characteristics as well as the nature of central metal ion. It has been found that the stability constant values increase with increasing the organic solvent in the reaction medium and decrease at higher temperatures. Thermodynamic functions [delta G, delta H, delta S] were evaluated and discussed