Diaquabis[1-hydroxy-2-(imidazol-3-ium-1-yl)-1,1′-ethylidenediphophonato-κ2O,O′]zinc(II)

In the title complex, [Zn(C5H9NO7P2)(2)(H2O)(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 center dot center dot center dot O hydrogen bonds. The molecules are linked into a chain by intermolecular O-H center dot center dot center dot O hydrogen bonds. Adjacent chains are further linked by O-H center dot center dot center dot O hydrogen bonds involving the aqua ligands. An N-H center dot center dot center dot O interaction is also observed.