Department of Chemistry, Faculty of Sciences, University of Razi, Kermanshah, I.R. IRAN
The complexation reactions between diacetyl monooxime (Damo), imidazole (Him), histamine (Hist) and histidine (His) with Co2+, Ni2+ and Cu2+ were studied potentiometrically in aqueous solution at 25 °C and m= 0.5 M KNO3. The overall stability constants log b's of species were obtained by computer refinement of pH-volume data using BEST computer program. Several models were tested and, based on the lowest sFIT , the best one is accepted. The main species in binary complexes are MAH, MA2, MA2H, MA2H2, (in MA3 and MA4 A=Him), and for ternary complexes are MAB, MA2B, MAB2 and MABH. The D log KMAB and log XMAB were calculated for MAB mixed complexes. The order found for the resulting stability constants vary as Co2+ < Ni2+ < Cu2+.