Formation constants, spectral and thermal properties of lanthanide complexes with D-penicillamine Disulfide

The complex-formation of the lanthanide[III] elements with D-penicillamine disulfide has been investigated in acidic and neutral media. The macroscopic protonation constants of the ligand and the formation constants of [Ln.Pds][+], [LN.[Pds][2][-], [Ln.Pds.OH] and [LN.Pds.[OH][2]][-] complexes were determined from pH-metric data using BEST computer program. Species distribution diagrams of the formed complexes are obtained and plotted using SPE and SPEPLOT computer programs. Elemental analyses of the solid complexes indicate the formation of 1:1 metal:ligand species. The binding sites in the complexes with a special regard to the possible role of-COO[-] and-NH[2] groups in the coordination have been discussed using infrared data. The complexes decompose in four steps as shown by their t.g.a. and d.t.a. analysis with the formation of Ln[2]O[2]SO[4] as a final product. Activation energy delta E[a] was calculated and correlated with type of complexed metal. Mechanism of thermal decomposition is proposed

Spectral and thermal studies of copper [II] and nickel [II] complexes of ethyl cyano [pyridyl hydrazone] acetate

Complexes of copper and nickel with ethyl cyano [pyridyl hydrazono] acetate [EC-3-PyHA and EC-4-PyHA] were synthesized and characterized. Results showed that the Cu [II] complexes are octahedral but the Ni [II] complexes are octahedral and square planar. DTA results indicated greater thermal stability for Ni [EC-3-PyHA]2 than for Cu [EC-3-PyHA]2