Complex formation by nickel and zinc with penicillamine and cysteine

Abstract

Stability constants of complexes formed by nickel(II) and zinc(II) ions with DL-penicillamine and L-cysteine have been calculated from pH titration data at 20° and I= 0·1 (NaCIO₄) by use of a computer-based method. With penicillamine, the nickel(II) complexes are simple mononuclear species of the types ML and ML₂^2–, whereas with zinc(II) protonated species are also present. Both metals form polynuclear and protonated complexes with cysteine. Copper(II) ion is reduced by these ligands.