Reactions of Complexation of Co(II), Ni(II), Cu(II), Cd(II) and Hg(II) Ions with Adenosine 5'-Diphosphate

The reaction of complexation has been studied in the systems of the ions: Co(II), Ni(II), Cu(II), Cd(II) and Hg(II) with adenosine 5'-diphosphate. The composition and stability constants of the complexes formed have been determined by the potentiometric method. The presence of the species type: MHL, ML x , and MLOH has been confirmed and their mode of coordination has been identified on the basis of the spectral data. In the acidic solution, the coordination dichotomy N(1)/N(7) has been found in all systems studied. At pH above 7, the dichotomy does not occur in the systems with Cu(II), while in the systems with Hg(II) only phosphate groups are involved in metallation. In the synthesized solid complexes of Cd(II) with AMP or ADP, the metal ion is bound by the donor nitrogen atom N(1), and in the complexes with ATP by the nitrogen atom N(7) of the nucleotide. Moreover, in the species with adenosine di- and triphosphate, the oxygen atoms of the phosphate groups are engaged in the complexation, while in the species Cd(AMP), similarly as in the liquid phase, the phosphate group is not involved in metallation.