Synthesis and Characterization of Metal Complexes of Schiff's Base Ligands Derived from 4-Carboxy Hydrazide-5, 6-Diphenyl-3(2-H)Pyridazone

A new ligand, 4-[carboxy-α-(2-hydroxyphenyl) ethylidene hydrazide-5,6-diphenyl-3(2H) pyridazinone (CHDP), were synthesized and characterized by 1H-NMR, IR spectra and elemental analysis. The dissociation equilibrium constant of CHEDP as well as the equilibrium constant for different M+n-CHEDP complexes were reported at different temperatures in 75% (v/v) dioxane-water media and constant ionic strength. The stability constants of CHDP complexes with transition and non-transition ions were evaluated. The thermodynamic parameters were also calculated and discussed. A series of mono nuclear protic M(HL), M(HL)2, ML(HL) and non-protic ML2 complex species were formed in solutions. The structure of the solid complexes formed between CHEDP and cobalt (II), copper (II) and iron (III) are substantiated by elemental analysis, mass spectra, thermal studies (TG and DSC) and IR spectra.