1-HYDROXYALKANE-1,1-DIYLDIPHOSPHONATES AS POTENT CHELATING-AGENTS FORMETAL-IONS - POTENTIOMETRIC AND SPECTROSCOPIC STUDIES OF COPPER(II) COORDINATION

Potentiometric and spectroscopic (EPR and absorption) studies have sho wn that two phosphonic groups bound to the same carbon atom serve as a very powerful binding site for Cu2+ ion in spite of the very high neg ative charge centred on these groups. The steric effects as well as a high negative charge enforce unusual geometries around the metal ion a nd the formation of 1:2 complexes is less favourable. These features o f the diphosphonic moiety mean that alkoxo-bridged dimer formation via the adjacent hydroxyl groups is less likely.