Tetra­ammonium μ-ethyl­enedi­amine­tetra­acetato-1κ(3) O,N,O′:2κ(3) O′′,N′,O′′′-bis­[trioxidotungstate(VI)] tetra­hydrate

The title compound, (NH(4))(4)[W(2)(C(10)H(12)N(2)O(8))O(6)]·4H(2)O, was obtained from a mixture of tungstic acid, ammonia and ethyl­enedi­amine­tetra­acetic acid (H(4)edta) in a 2:4:1 ratio. The anion of the complex contains two WO(3) units and one bridging edta(4−) ligand. Each central metal atom is tridentately coordinated by nitro­gen and two carboxyl­ate groups of the edta(4−) ligand, together with the three oxido ligands, producing a distorted octa­hedral coordination environment around each tungsten atom. The center of the carbon–carbon bond of the ethyl­ene bridge represents a crystallographic inversion center. The crystal structure consists of a three-dimensional supra­molecular framework built up by the dinuclear cations, the ammonium counter-ions and the solvent water mol­ecules via hydrogen bonds of the N—H⋯O and O—H⋯O type. [Image: see text]