[(5‐Bromo­pyridinium‐2‐ylamino)(phosphono)meth­yl]phospho­nate

The title compound, C₆H₉BrN₂O₆P₂, a micromolar inhibitor of the farnesyl pyrophosphate synthase, is a Z‐isomer zwitterion with one negative phospho­nate group and a protonated pyridine N atom. Two types of ribbons, both parallel to the a axis, formed by several centrosymmetrically related O—H⋯O and N—H⋯O hydrogen bonds are generated in the crystal structure. The resulting two‐dimensional (001) `double‐layered' networks are joined into a three‐dimensional network via inversion‐related halogen–oxygen inter­actions.