o-hydroxyaroyl-isonicotinoyl hydrazones as chelating agents with divalent transition metal ions

Summary Two series of bivalent metal complexes of the type M(Sal)· xH₂O and M(Naph) have been synthesized; where M = Co, Ni, Cu, Zn, Pd and Cd, and H₂-Sal and H₂-Naph are salicylaldehyde and o-hydroxynaphthaldehyde isonicotinoyl hydrazones which acted as dibasic terdentate ligands. The polymeric nature and coordination sites of the complexes have been characterized by elemental, d.t.a. and t.g.a analyses, molar conductance, pH, room temperature magnetic susceptibility and spectral (i.r., ¹H n.m.r, u.v.) measurements. The protonation constants of the ligands have been determined potentiometrically at different temperatures, ionic strengths and at different EtOH-H₂O compositions.