Synthesis, Solution, and Structural Characterization of Tetrahydrofuranyl-2,2-Bisphosphonic Acid Disodium Salt

Bisphosphonates are biologically relevant therapeutics for bone disorders and cancer. Reaction of γ-chlorobutyric acid, phosphorus acid, and phosphorus trichloride without the use of solvent gave the tetrahydrofuranyl-2,2-bisphosphonate sodium salt (Na(2)H(2)L). The Na(2)H(2)L was isolated, characterized in solution by (1)H, (13)C, and (31)P NMR spectroscopy and in solid state by single X-Ray crystallography. The crystal structure showed that the Na(2)H(2)L forms in the crystal infinite two-dimensional sheets stacked one parallel to the other. A comparison of the chelating properties of H(2)L(2−) with similar hydroxyl bisphosphonate ligands shows that the strength of the Na–O(furanyl/hydroxyl) bond is directly related to the total charge of the ligand anion.