Narrow Results

Equilibrium constants (1:1) for the reactions of cadmium(II) and lead(II) with water-soluble free base porphyrins of differing basicities (pK₃) are reported. Soft porphyrins with low pK₃ values favor the softer Cd(II), while harder porphyrins with higher pK₃ values have more affinity for the relatively harder Pb(II) ion.