Electrochemical investigations of the nickel(II)-penicillamine system : inert and labile complexes detected by polarography

The effect of penicillamine on nickel diffusion current demonstrate s that NiL(2)(2-)is a kinetically inert complex whereas Nit is labile (L2- = (CH3)(2)C(S-)CH(NH2)COO-)). The difference in kinetic stabili ty between the analogous bis-ligand complexes of Ni(II) with either p enicillamine or cysteine is tentatively explained taking into accoun t their structures. It is suggested that nickel detoxication by chela te ligands depends on the inert character rather than on the thermod ynamic stability of the relevant nickel complex.