| Abstract |
Equilibrium study on the mixed ligand complex formation of Cu-II with biguanide(Bg) and glycine (HG), indicated the formation of the complexes: Cu(Bg)(2+), Cu(Bg)(2)(2+), Cu(Bg-H)(Bg)(+), Cu(Bg-H)(2), Cu(Bg)(OH)(+), Cu(Bg-H)(OH); Cu(G)(+), Cu(G)(OH), Cu(G)(2); Cu(G)(Bg)(+), Cu(G)(Bg-H); (G)Cu(Bg)Cu(G)(2+), (G)Cu(Bg-H)Cu(G)(+), and (G)Cu(Bg-2H)Cu(G). From the deprotonation constants of coordinated biguanide (Bg) in the complexes Cu(Bg)(OH)(+), Cu(Bg-H)(Bg)(+) and Cu(G)(Bg)(+), the Lewis basicities of the coordinated ligand species (B-H)(-), OH- and glycinate (G(-)) were found to be of the order: (Bg-H)(-)>> OH-> G(-). Bridging (N-1-N-4, N-2-N-5) tetradentate mode of coordination by biguanide species Bg, (Bg-H)(-) and (Bg-2H)(2-) was indicated from the occurrence of biguanide-bridged dinuclear mixed ligand complexes (G)Cu(Bg)Cu(G)(2+), (G)Cu(Bg-H)Cu(G)(+), (G)Cu(Bg-2H)Cu(G) in the complexation equilibria. |
