Tris[tris-(1,10-phenanthroline-κN,N')iron(II)] dodeca-tungstoferrate dihydrate.

The title compound, Fe(C(12)H(8)N(2))(3)[FeW(12)O(40)]·2H(2)O, was prepared under hydro-thermal conditions. The discrete Keggin-type FeW(12)O(40) heteropolyoxoanion has threefold symmetry, with the Fe(II) atom located on the threefold rotation axis. The central FeO(4) tetra-hedron in the anion shares its O atoms with four W(3)O(13) trinuclear units, each of which is made up of three edge-shared WO(6) octa-hedral units. The Fe(II) atom in the complex cation, viz Fe(phen)(3) (phen is 1,10-phen-anthroline), shows a slightly distorted octa-hedral geometry defined by six N atoms from three phen ligands. The polyoxoanions pack together with the cations, with the disordered water mol-ecules located in voids; the site occupancy factor for each water O atom is 0.33.