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

In the title complex, [Zn(C(5)H(9)NO(7)P(2))(2)(H(2)O)(2)], the zinc atom is coordinated by two bidentate zoledronate [zoledronate = (2-(1-imidazole)-1-hydr­oxy-1,1′-ethyl­idenediphophonate)] ligands and two water mol­ecules. The coordination number is 6. There is one half-mol­ecule in the asymmetric unit with the zinc atom located on a crystallographic inversion centre. 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. There are two intra­molecular O—H⋯O hydrogen bonds. The mol­ecules are linked into a chain by inter­molecular O—H⋯O hydrogen bonds. Adjacent chains are further linked by O—H⋯O hydrogen bonds involving the aqua ligands. An N—H⋯O inter­action is also observed.