Copper (II) and zinc (II) with 2-(4-Chloroaniline)-1,2-Diphenyl-1-Ethanonethiosemicarbazone in Solution: Possible Competition for Ligand Coordination Sites

Abstract

Study of complex formation on dissolution of the 2 systems (4-chloroaniline) -1,2-diphenyl-1-etanonatiosemicarbazona / copper II and zinc II was performed. The potentiometric titration was used to determine the stability constant of the ligand and its complexes with these ions, in an acetonitrile: water 8: 1 (NaCl 0.1 mol · dm-3 as ionic strength). Four protonation constants were determined. The second and third protonations can occur simultaneously. In the same way, 6 copper II complexes and 4 zinc II complexes have been found in the data processing. In addition, it was possible make the study of the competition between ions Cu (II) and Zn (II), for the coordination sites of ligand. From data fit, we had three heterodinuclear species: ZnCuHL5+, ZnCu2L2(OH)5+ y ZnCuL(OH)5-. All mixed complexes exhibit stability values higher than the preceding mono-complex species.