Structural chemistry of 1-hydroxyethylidenediphosphonic acid complexes

The structural features of complexes of 1-hydroxyethylidenediphosphonic aci d (HEDP) with different metals (geometric isomerism, dentate numbers and th e mode of coordination of organophosphorus ligand, the structural type and degree of oligomerization, regular distortions of the coordination polyhedr on, and the mutual influence of the ligands) are considered. The dependence s of the complex structures and of the degree of deprotonation of the HEDP ligands on the synthesis conditions (solution pH and metal : HEDP ratio). o n the nature of the metal and the outer-sphere cation, on the composition o f the hydrate sphere, and on the availability of the accompanying ligands a re also established.