Potentiometric conductometric and spectrophotometric studies on co2+, Ni2+, Cu2+, Pd2+ and Pt2+ complexes with some naphthol derivatives

ABSTRACT

The ionization constants [pka] of some naphthol derivatives were determined potentiometrically in 40 percent ethanolic solution. The stability constants of divalent Co, Ni, Cu, Pd and Pt complexes with naphthol derivatives were determined potentiometrically, log Beta[1] and Log Beta[2] values being calculated. The correlation between the basicity of the ligands and stability of complexes is discussed. Conductometric titrations of divalent Co, Ni, Cu and Pt with the naphthol derivatives were carried out to give further insight into the stoichiometric composition of the complexes formed in solutions. The divalent Ni and Pd complexes with NNWA were studied spectrophotometrically and the stoichiometries of the complexes formed were established. The results indicate that all ligands form 11 and 12 [M L] complexes and the influence of pH. time, sequence of addition and foreign ions on the formation of the complexes was studied. Beer's law was satisfactorily obeyed up to 6 ppm and 7 ppm for Ni and Pd respectively