Abstract
Stability constants of bivalent (Mn2+, Co2+, Ni2+, and Cu2+) metal ion complexes with rhodanine azosulfonamide derivatives have been determined potentiometrically in 0.1 M-KCl and 30 vol. % ethanol-water mixture. The stability constants of the formed complexes increase in the order Mn2+, Co2+, Ni2+, Cu2+. The influence of substituents on the stability of the complexes was examined on the basis of electron repelling property of the substituent. The effect of temperature on the stability of the complexes formed was studied and the corresponding thermodynamic quantities (DeltaG, DeltaH, and DeltaS) were derived and discussed. The stoichiometries of these complexes were determined conductometrically and indicated the formation of 1:1 and 1:2 (n(metal):n(ligand)) complexes.