Mercury(II) complexes with sulfhydryl containing chelating agents: Stability constant inconsistencies and their resolution

Abstract

An experimental study has been carried out to provide information on the nature of the inconsistencies in previously reported values of the stability constants of mercury(II) complexes with sulfhydryl containing chelating agents. Stability constants have been determined for the mercury(II) complexes with d,l-penicillamine (PA), N-Acetyl-d,l-penicillamine (NAPA). 2,3-dimercaptopropanesulfonate (DMPS), and 2,3-dimercaptopropanol-1 (BAL) using a titration procedure involving simultaneous measurements with a glass and a mercury electrode. The stability constants obtained in this manner were of the order of 1035-1044. Chelating agents with two sulfhydryl groups give complexes with mercury(II) whose K1 values are greater by a factor of 107 than those which contain but a single sulfhydryl group. Arguments are presented in favor of the validity of such large values. © 1980.