Synthèse et étude comparée des propriétés complexantes de dérivés de l'acide Methylène Diphosphonique
Abstract
Two original acid derivatives of methylene diphosphonic acid (MDP) with two inequivalent phosphorus atoms have been synthesised: [(thiophosphonato)-methyl]phosphonic acid, (MDPS), and [(isopropyiamido phosphonato)-methyl] phosphonic acid, (MDPN). A poten- tiometric study allowed to define the stoechiometry of the complex formed between MDP and magnesium (II) in alcaline medium and a 31P NMR study proved the dissymetric structure of this MDPMg2+ complex. The displacement of the coordination equilibrium between Black Eriochrome T and magnesium (II) permitted to compare the coordination strength of MDP, MDPS and MDPN with the cation Mg2+.