The interaction of Cr(III), Mn(II), and Fe(III) ions with cyclodiphosphazane and thiourea monophosphazene derivatives was followed potentiometrically with the aim of determination of stability constants of (metal : ligand) 1:1 and 1:2 binary, and 1:1:1 ternary chelates at 25The stability of the complexes of both ligands was found to be Fe (III) > Mn(II) < Cr(III). The concentration distribution of the species formed in solution was evaluated. Binary and ternary solid complexes were prepared with the purpose of structural characterization using elemental analyses, molar conductance, IR, 1 HNMR and electronic spectra and thermogravimetric analysis. The data show that the ligands behave as neutral bidentate ligands, forming neutral chelates of monomeric nature.
Novel neutral polynuclear Ni II chelates of l-cysteine (lcyst) or d-penicillamine (d-pen) with dicyandiamide (dcda) were synthesized and characterized using elemental analysis, UV, CD, reflectance, and IR spectroscopy and/or thermogravimetric and X-ray analysis. The obtained dinuclear compounds add important information about the chemistry of nickel(II) ions, which form types of bonds that cannot be obtained with other metal ions such as Co II . These dinuclear nickel compounds contain four-membered rings with two sulfur and two nickel atoms. Electronic transitions were elucidated from reflectance, CD and absorbance spectroscopy and confirm a distorted square * Dr. A. A. M. Gad Fax: +2-097-3480450 E-Mail: a_gad53@yahoo.com [a]
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