Spectroscopic and potentiometric studies of Co (II) and Ni (II) complexes with N-(I-Morpholinobenzyl) semicarbazide

Abstract

The Schiff base complexes of cobalt(II) and nickel(II) were synthesized by refluxing the mixture of ethanolic solutions of the Schiff base and metal(II) chlorides, respectively. The complexes were characterized by gravimetry, spectrophotometry, potentiometry, molar conductance and infrared analyses. The N-(1- morpholinobenzyl)semicarbazide Schiff base and its complex compounds are not soluble in water, slightly soluble in most common organic solvents but are readily soluble in methanol and ethanol. The molar conductance of the cobalt (II) and nickel(II) schiff base complexes determined are in the range 5.38 - 6.03 ohm-1cm2mol-1, suggesting their nonelectrolytic nature. The dissociation constant, pKa, of N-(1- morpholinobenzyl)semicarbazide Schiff base determined is 5.40. The standard Gibb’s free energy of cobalt(II) and nickel(II) N-(1- morpholinobenzyl)semicarbazide Schiff base complexes determined are -70.78KJmol-1 and - 68.06KJmol-1, respectively. The ratio of metal ion to Schiff base determined potentiometrically and spectrophotometrically for the complex compounds is 1: 2. The IR spectrum of the Schiff base shows bands observable in the two Schiff base complex compounds, indicating the coordination of the Schiff base to the cobalt(II) and nickel(II) ions.

Key Words: Schiff base, azomethine, benzyldehyde, potentiometry, spectrophotometry, morpholine.