ABSTRACT
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
Subject(s)
Chelating Agents/chemistry , Temperature , Schiff Bases/chemistry , Ninhydrin/chemistry , Hydrazines/chemistry , IsatinABSTRACT
Synthesis and characterization of Schiff base ligand of ninhydrin with S-methylhydrazinecarbodithioate and its Cr [III], Mn [II], Fe [III], Co [II], Ni [II], Cu [II], Zn [II] and Cd [II] complexes were reported. Elemental analysis, molar conductivity, magnetic moment, spectral 1H NMR, UV/Visible and IR data have been used to characterize these complexes. It has been found that the ligand behaves as mononegative ONS tridentate towards divalent metal ions forming 1:2 [metal:ligand] stoichiometry and as mononegative NS bidentate towards trivalent metal ions forming 1:3 [metal: ligand] stoichiometry. For all complexes, a non-electrolytic nature was observed. Some available spectral parameters were calculated. Octahedral and distorted octahedral geometries were proposed for the complexes on the basis of magnetic and spectral measurements