Aquabis[1-hydroxy-2-(imidazol-3-ium-1-yl)-1,1′-ethylidenediphophonato-κ(2) O,O′]zinc(II) dihydrate

In the title complex, [Zn(C(5)H(9)NO(7)P(2))(2)(H(2)O)]·2H(2)O, the zinc atom is coordinated by two zoledronate anions [zoledronate = (2-(1-imidazole)-1-hydr­oxy-1,1′-ethyl­idenediphophonate)] and one water mol­ecule. The coordination number is 5. There is one half-mol­ecule in the asymmetric unit, the zinc atom being located on a twofold rotation axis passing through the metal centre and the coordinating water O atom. The anion exists as a zwitterion with an overall charge of −1; the protonated nitro­gen in the ring has a positive charge and the two phospho­nates groups each have a single negative charge. Inter­molecular O—H⋯O hydrogen bonds link the mol­ecules. An N—H⋯O inter­action is also present.