μ(3)-Dodeca-tungsto(V,VI)aluminato-κO:O':O''-tris-[aqua-bis-(ethyl-ene-diamine-κN,N')copper(II)].

The title compound, [AlCu(3)W(12)O(40)(C(2)H(8)N(2))(6)(H(2)O)(3)], was prepared under hydro-thermal conditions. The Cu(2+) ion displays an elongated octa-hedral geometry defined by one bridging O atom from the polyoxidoanion and a coordinated water mol-ecule in axial positions and four N atoms of the two chelating ethyl-enediamine (en) ligands in equatorial positions. The one-electron reduced AlW(12)O(40) anion coordinates three Cu(en)(H(2)O) fragments, generating a neutral tri-supported Keggin-type polyoxidometalate (POM). This tri-supported POM is located in a special position of [Formula: see text] symmetry and therefore O atoms from the central AlO(4) tetra-hedron are disordered over two sets of sites. Disorder is also observed for three other bridging O atoms of the POM. In the crystal, mol-ecules are connected via N-H⋯O and O-H⋯O hydrogen bonds, forming a three-dimensional framework.