تحضير وتشخيص ليكاندي قواعد شف المشتقة من امينات اروماتية و عدد من معقداتها الفلزية مع دراسة بعض الخصائص الثرموديناميكية لها

Preparation and Characterization of Schiff bases ligands derived from aromatic amines and several of their metal complexes, with a study of some of their thermodynamic properties.

Abstract

The study included the preparation and diagnosis of bi dentate ligands and     their complexes with metal ions of bivalent elements (nickel, copper, zinc, cadmium, and mercury). The first ligand was prepared in one step that included the reaction of (acetylacetone dissolved in absolute ethanol with (4-phenoxy aniline) in the presence of glacial acetic acid by Reflux reaction method.
The second ligand was prepared from the reaction of (acetylacetone with (2-ethyl aniline) in the presence of (NaOH 10%) by Reflux method .ligands and the prepared complexes were characterized by available spectroscopic methods. Such as the infrared spectrum (FT-IR), the ultraviolet-visible spectrum, measurement of the melting point and elemental analysis(C.H.N ), in addition to the proton nuclear magnetic resonance (1H-NMR) spectrum and the mass spectrum of the ligands, and the molar conductivity and magnetic susceptibility measurement.
From the study of spectroscopic methods and magnetic susceptibility, the stereoscopic shapes of the prepared complexes were proposed, as it was found that the complexes of the first and second ligands possess an electrolytic character, except of [HgL1Cl2] and [NiL2Cl2], which maintains a non-electrolytic character and a tetrahedral shape around the bivalent ions of nickel, copper, zinc, cadmium and mercury with the ligands L1, L2 respectively. The best conditions for the formation of complexes were also determined, such as the acid function, the concentration of the ligand solution, the period for the stability of the formed complexes, the effect of temperature on the stability of the complexes, and the ranges of concentrations that obey the Beer-Lambert law were determined through calibration curves within the range (1×10-6 -9×10-4) The possible structures of the prepared complexes were also studied by finding the ratio of the metal ion to the ligand (M:L) using the molar ratio method. The results indicate that the ratio was (1:1) for all complexes. The stability constants were calculated for the complex of nickel, copper, zinc, cadmium, and mercury, respectively. for the first and second ligands. The thermodynamic functions (ΔG, ΔH, ΔS) were also calculated for the prepared complexes under study at temperatures (278-298 K). It was found that the stability constants of the complexes increase with increasing temperatures, because they are endothermic reactions, and the formation reactions of all complexes occur spontaneously, This is what was observed through the free energy change values.