Studies of the complex formation properties of pyridazine and 2-aminopyrimidine towards Co(2), Ni(2), Cu(2), Zn(2) and Cd(2) in aqueous solutions

The complexation of Co(2), Ni(2), Cu(2), Zn(2) and Cd(2) with pyridazine and 2-aminopyrimidine was studied potentiometrically and spectrophotometrically at 25 deg C and constant ionic strenght of 0.5 (KNO3). The composition, structure and stability constants of compounds formed in the aqueous solutions have been determined. It is shown that diazine rings exhibit a greater π-acceptor character towards bivalent metal cations than imidazole and pyridine and somewhat smaller than the other azoles. 3 figs., 3 tabs., 32 refs. (author)