Amino-substitutedgem-diphosphonic acids: Dissociation mechanism and the structure of species in aqueous solutions

The mechanism of dissociation of amino-substitutedgem-diphosphonic acids R2N(CH2) n CR'(PO3H2)2 with different lengths of the alkylidene chain and different substituents at the N atom was studied by vibrational (IR, Raman) and NMR (1H,14N,31P) spectroscopy using data of conformational analysis (molecular mechanical) data. The important role of intramolecular H-bonds and cyclic solvates for the stabilization of various conformations and tautomeric forms of ions was demonstrated. The spectral data that allow one to consider thegem-diphosphonate group as a single acidic center were found.