Complexation properties of ethylenediaminetetramethylenephosphonic acid (EDTMP) with Al-III and (VO)-O-IV

The complexation properties (including stoichiometries and stability constants of the complexes formed) of ethylenediaminetetramethylenephosphonic acid with Al-III and (VO)-O-IV were studied in aqueous solution at an ionic strength of 0.2 M KCl, at 25 degreesC by means of pH potentiometry. For Al-III both mononuclear (AlLHn) and dinuclear (Al2LHn) species were found in solution, whereas for (VO)-O-IV only mononuclear complexes were detected, For each metal ion, a solid complex was isolated at acidic pH and was characterized stoichiometrically. H-1 and P-31 NMR (for Al-III), UV/Vis and EPR (for (VO)-O-IV) spectra were used to confirm the potentiometric results and to suggest the most probable binding mode of the complexes formed in solution. (C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004.