Mixed ligand complexes of copper(II), nickel(II), cobalt(II) & zinc(II) with iminodiacetic acid as a primary ligand & imidazole as a secondary ligand

335-336The stability constants of the title mixed ligand complexes determined potentiometrically in aqueous medium, follow the order: Cu > Zn > Ni > Co. KMLA values are greater than K4 (Im) for simple imidazole complexes. At higher concentrations of imidazole (MLA2 systems), Cu(II) and Ni(II) form both MLA and MLA2 types of complexes, but with Co(II) and Zn(II) only MLA is formed