Atef A. T. Ramadan

Metal chelates of azo-pyridazine dyes: Chelating tendencies of benzoylacetone-monohydrazone-3-hydrazino-4-benzyl-6-phenylpyridazine (bahp)

The synthesis, acid-base equilibria and metal-ion chelating tendencies of BAHP are reported. From potentiometric equilibrium measurements of hydrogen-ion concentration at 30 degrees and ionic strength 0.10M (KNO(3)), in 75% dioxan-water medium, the values of the stability constants of some BAHP complexes with transition, non-transition and lanthanide ions have been evaluated. Probable structures of the metal chelates are inferred from the electronic absorption spectra and infrared examination of the solid copper complex. The use of BAHP as an analytical reagent for the spectrophotometric determination of copper, nickel and cobalt ions is discussed.

Metal chelates of azo-pyridazine dyes-II : Chelating tendencies of diacetyl-, benzil- and benzoylethane-monohydrazone-3-hydrazino-4-benzyl-6-phenylpyridazine

Abstract The diacetyl-(DAHP), benzil-(BHP) and benzoylethane-(BEHP) derivatives of 3-hydrazino-4-benzyl-6-phenylpyridazine have been prepared and characterized. Their acid-base properties and their equilibria with transition metal ions in 75% dioxan-water solvent at 30°C have been investigated by pH titrimetry. The role of proton and metal ion solvation by the organic solvent has been discussed in view of the results obtained for the lanthanide-BHP systems in different media. Probable structures of the metal chelates are given based on potentiometric data and spectral results for the solid copper chelates. The possibility of forming MHL species were inferred from electronic absorption measurements at different pH values. The use of BHP as an analytical reagent for the determination of copper spectrophotometrically or as a metallochrom indicator in the complexometric titration of Cu(II) ion is also discussed.

The thermodynamics of complexation of transition and lanthanide ions by 3-(α-carboxymethylaminobenzyli-denehydrazino)-5,6-diphenyl-1,2,4 triazine (HipHt)

The metal-ligand stability constants of the Ni(II), Co(II), Zn(II), Mn(II), Cd(II), Fe(III), UO2(II) and Ln(III) chelates of HipHT were determined in 75% (v/v) dioxane-water medium at 10, 20 and 30°C and μ = 0.1M(KNO3). The thermodynamic parameters for the proton-ligand and metal-ligand stability constants were obtained by the temperature coefficient method. The thermodynamic functions ΔG and ΔH of the complexes were analyzed in terms of the electrostatic (el) and non-electrostatic (non) components. The values of ΔHnon and ΔHel show a linear variation with the hardness and softness Eνn of the metal ion and with the heat of hydration ΔHh, of the metal ion, respectively. HipHT behaves as a diprotic tridentate (NNO) donor towards the metal ions, as inferred from the infrared spectra of its metal chelates.

Synthesis and Characterization of New Transition and Actinide Metal Complexes of a Hydrazone Ligand. Mixed‐Ligand Complexes, Pyrolysis Products, and Biological Activity

Abstract The chelating properties the hydrazone ligand 2‐carboxyphenylhydrazo‐ethylcyanoacetate (H2L) have been studied. A new series of binary mononuclear complexes were prepared from the reaction of the hydrazone ligand (H2L) with the metal ions, Cd(II), Cu(II), Ni(II), Co(II), Th(IV), and UO2(VI), in the presence of LiOH as a deprotonating agent. The binary Cu(II) complex of H2L was reacted with the ligands 1,10‐phenanthroline or 2‐aminopyridine to form mixed‐ligand complexes. The binary complexes of Cu(II) and Ni(II) are suggested to have octahedral configurations. The Cd(II) and Co(II) complexes are suggested to have tetrahedral and/or square‐planar geometries, respectively. The Th(IV) and UO2(VI) complexes are suggested to have octahedral and dodecahedral geometries, respectively. The mixed‐ligand complexes have octahedral configurations. Also, new complexes were obtained pyrolytically as the previous complexes decompose through several isolable as well as non‐isolable intermediates during heating. The structures of all complexes and the corresponding thermal products were elucidated by elemental analyses, conductance, IR and electronic absorption spectra, magnetic moments, 1H NMR and TG–DSC measurements, as well as by mass spectroscopy. The ligand and some of the metal complexes were found to activate the enzyme pectinlyase.

The thermodynamics of lanthanide complexing by bis(5,6-diphenyl-1,2,4-triazine-3-ylhydrazinocarbonyl) (DPTHC)

Abstract The free energies, enthalpies and entropies of complexation of lanthanide ions by bis(5,6-diphenyl-1,2,4-triazine-3-ylhydrazinocarbonyl) (DPTHC) have been determined by potentiometry in 75% (v/v) dioxane-water and 0.10 M KNO 3 ionic strength. The data obtained support the interpretation of an expanded solvation sphere through the lanthanide series. Relatively large values of entropy of formation for chelation process (Δ S 1 and Δ S 2 ) imply an increase hi the hydration number from lanthanum to lutetium and also the possibility of dioxane coordination in the solvent sphere. Probable structures of the metal chelates are inferred from IR examination of the solid copper, neodymium and ytterbium complexes.

Synthesis and properties of iron(II) and iron(III) complexes with 3-(α,γ-dicarboxy-n-propylidene-hydrazino)-5,6-diphenyl-1,2,4-triazine (DCPT)

SummaryProton-ligand formation constants ofDCPT and metal-ligand formation constants of its complexes with Fe(II) and Fe(III) have been determined potentiometrically at 10, 20, 30, and 40°C in 75% (v/v) dioxane-water at 0.10M ionic strength (KNO3). The thermodynamic parameters ΔG, ΔH, and ΔS have also been evaluated. The possibility of formingM(HL),M(HL)2, andM(HL)3 species was substantiated from potentiometric and electronic absorption measurements. The values of the stability constants logKM(HL), log

Metal chelates of azo-pyridazine dyes III chelating tendencies of pyruvic and hippuric monohydrazone-3-hydrazino-4-benzyl-6-phenylpyridazine

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Azo Complexes of Cu(II), Co(II), Ni(II), Cd(II), Th(IV), and UO2(VI) Ions. Mixed‐Ligand Complexes, Pyrolysis Products and Biological Activity

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