Crystal structure of zwitterionic 3-(2-hydroxy-2-phosphonato-2-phosphonoethyl)imidazo[1,2-a]pyridin-1-ium monohydrate (minodronic acid monohydrate): a redetermination

Abstract

In a previous study, the X-ray structure of the title compound, C9H12N2O7P2·H2O, was reported [Takeuchi et al., (1998). Chem. Pharm. Bull. 46, 1703–1709], but neither atomic coordinates nor details of the geometry were published. The structure has been redetermined with high precision as its detailed knowledge is essential to elucidate the presumed polymorphism of minodronic acid monohydrate at room temperature. The molecule crystallizes in a zwitterionic form with cationic imidazolium[1,2a]pyridine and anionic phosphonate groups. The dihedral angle formed by the planes of the pyridine and imidazole rings is 3.55 (9)°. A short intramolecular C—H...O contact is present. In the crystal, molecules are linked by O—H...O, N—H...O and C—H...O hydrogen bonds and π–π interactions [centroid-to-centroid distance = 3.5822 (11) Å], forming a three-dimensional structure.

Keywords

• crystal structure
• bisphosphonate
• polymorphism
• minodronic acid
• hydrogen bonds
• redetermination