Structure of substituted aminomethanebisphosphonic acids analyzed by NMR spectroscopy and X-ray powder diffraction

The 31P NMR spectra of a series of substituted aminomethanebisphosphonic acids (AMBAs) are reported. The AMBAs may crystallize as anhydrates or in hydrated form. The appearance of more than one 31P NMR signal in the solid state NMR spectra of AMBAs is an indication for a complex molecular order with non-equivalent phosphorus sites.