Equilibrium studies of mercury(II) complexes with penicillamine.
The complex-formation equilibria of mercury(II) with penicillamine have been investigated in acidic and neutral conditions. A liquid-liquid extraction method using dithizone as auxiliary ligand was applied for the determination of the stability constants of three differently protonated 1:2 metal/ligand complexes formed at pH<3. Evidence has been found by potentiometry and confirmed by Raman spectroscopy for the existence of 1:3 metal/ligand complex besides 1:1 and 1:2 species at pH>4. The stability constants of HgL(3)H(3)(-) and HgL(2)H(-) complexes as well as the macroscopic protonation constants of the ligand were determined from pH-metric data. The binding sites in the complexes with a special regard to the possible role of COO(-) and NH(2) groups in the coordination have been discussed.
Kõszegi-Szalai
H
H
National Institute of Pharmacy, Budapest, Hungary.
Paál
T L
TL