Mixed-ligand stability constants of divalent metal ions with glycine and hydroxamic acids

(T)he thermodynamic mixed ionization constants, pK(AB)(H) of N-m-chlorophenyl-p-substituted benzohydroxamic acids and glycine have been determined in 0.083 to 0.24 mole fraction of dioxane (n(2)) 25 degreesC. The mixed pK(AB)(H) are correlated with the Hammett equation. The determined stability constants have been found to follow the order Pd(II) > Cu(II) > Ni(II) > Zn(II) > Co(II) > Fe(II) > Mn(II) and these also follow the order of basicities of the ligands. The linear free-energy relationship for the particular set of metal ions and the set of ligands is calculated and compared.