Synthesis, magnetic and electrochemical properties of binuclear copper(II) complexes of pyridoxal hydrazones

Abstract

Some new binuclear copper(II) complexes with pyridoxal benzoylhydrazone (PBH), pyridoxal o-hydroxylbenzoyl- hydrazone (PHBH), pyridoxal picolinoylhydrazone (PPH), pyridoxal nicotinoylhydrazone (PNH), and pyridoxal isonicotinoylhydrazone (PINH) have been synthesized and characterized by analytical, magnetic, spectral, ESR and electrochemical methods. All the complexes exhibit normal magnetic moments at room temperature. The variable temperature magnetic moments, however, indicate the presence of very weak intramolecular antiferro- magnetic interactions (−2J ≈˜90 cm−1) in between the copper(II) centers in the complexes. The ESR spectral data at 77 K are characteristic of binuclear Cu---Cu complexes and exhibit a seven-line pattern in the low field gl region. The cyclic voltammograms of each complex showed two oxidation waves attributed to Cu2II,II→Cu2II,III and Cu2II,III→Cu2III,III processes at significantly low potentials.