Nickel alendronate

The title compound {sys­tematic name: bis(μ(2)-dihydrogen 4-aza­niumyl-1-hy­droxy­butane-1,1-di­phos­pho­n­ato)bis­[aqua­(dihydrogen 4-aza­nium­yl-1-hy­droxy­butane-1,1-diphospho­n­ato)nickel(II)] dihydrate}, [Ni(2)(C(4)H(12)NO(7)P(2))(4)(H(2)O)(2)]·2H(2)O, was synthesiized under hydro­thermal conditions. Its structure is isotypic with the Co(II) analogue. The crystal structure is built up from centrosymmetric dinuclear complex mol­ecules and the structure is reinforced by a net of inter­molecular O—H⋯O and N—H⋯O hydrogen bonds. One water mol­ecule is bound to the Ni(II) atom in the octahedral coordination sphere, while the second is part of the inter­molecular hydrogen-bond system.