Physical studies of some hydrazinobenzoic acid complexes

The stability constants of complexes of 2-hydrazinobenzoic acid and 4-hydrazinobenzoic acid with Ni (II), Cu (II), Zn (II), Cd (II), and Hg (II) were determined potentiometrically at different temperatures. The thermodynamic parameters, DeltaGdegrees, DeltaHdegrees, and DeltaSdegrees were calculated and proved that the complexation process is spontaneous and endothermic. The thermodynamic functions were analyzed in terms of electrostatic and non-electrostatic components and the results reveal that ionic bonds are formed between the studied ligands and metal ions. Conductometric titration was shown that the stoichiometry of the formed complexes are M:L and M:2L. The structure of the prepared solid complexes was characterized using IR, H-1 NMR, C-13 NMR spectroscopies as well as X-ray diffraction technique. Finally electrical conductivity of the ligands and their copper complexes was measured and shown that the ligands have a semiconductor behaviour.