Synthesis and Characterization of Copper(II), Nickel(II), and Cobalt(II) Chelates with Tridentate Schiff Base Ligands Derived from 4‐Amino‐5‐hydroxynaphthalene‐2,‐7‐disulfonic Acid

Abstract

New Schiff bases have been synthesised by the condensation of 4‐amino‐5‐hydroxynaphthalene‐2,7‐disulfonic acid mono sodium salt with o‐vanillin (H2L1) and salicylaldehyde (H2L2), and their complexes with copper(II), cobalt(II) and nickel(II) have been prepared. All compounds were characterized by elemental analyses, FT‐IR, electronic spectral data, magnetic moments, mass spectroscopy and molar conductance. The 13C NMR and 1H NMR spectra of the Schiff base ligands have been recorded. The results suggested that the Schiff bases are coordinated to the metal ions through the phenolic oxygens and azomethine nitrogen to give mononuclear complexes. Magnetic measurements and absorption spectral data reveals that the copper and nickel complexes have tetrahedral geometry. All compounds were found to be non‐electrolytes in aqueous solutions. According to mass spectroscopy and thermogravimetric data, all complexes have one water molecule coordinated to the metal ion.