| Abstract |
Equilibrium study on the mixed-ligand complex formation of the 3d(M-II) ions (M = Co, Ni, Cu and Zn) with glycine (H3N+CH2COO-, GlyH(+/-)) and 4,6-dimethyl-2-guanidinopyrimidine [H2NC(=NH)NH\CN2(CCH3)(2)CH\, Gup], indicate variety of binary and mixed-ligand complexes [M(Gly)(+)], [M(Gly)(OH)], [M(Gup)(2+)], [M(Gup-H)(+)] [M(Gup)(2)(2+)], [M(Gup-H)(Gup)(+)], [M(Gup-H)(2)], [M(Gly)(Gup)(+)] and [M(Gly)(Gup-H)] with Cu-II and Ni-II, the mixed-ligand complexes [M(Gly)(Gup)(+)] and [M(Glv)(Gup-H)] dominate the pH range of biological relevance, whereas, with Co-II and Zn-II the (M(Gly)(+)] and [M(Glv)(OH)] complexes are the major metal containing species under the same condition Formation constants of the proton-ligand and metal-ligand complexes at 25 +/- 1 degrees C in 50\% v/v ethanol-water medium (ionic strength, I = 0 1 mol dm(-3)) mere evaluated by computer based pH-metric titration;method Complex formation equilibria were elucidated by analyzing the speciation curves and correlated with the modest of coordination, of the ligands |
