SYNTHESIS AND CRYSTAL-STRUCTURE OF MONOCLINIC FE2(SEO4)3

Crystals of monoclinic Fe2(SeO4)3 were synthesized under hydrothermal conditions. The structure was determined by single crystal X-ray methods and refined in space group P2(1)/n with 2 646 independent reflections (sin-theta/lambda < 0.7 angstrom-1) to R = 0.033, R(w) = 0.037: a = 8.530 (2) angstrom, b = 8.888 (2) angstrom, c = 11.952 (2) angstrom, beta = 91.13 (1)-degrees, V = 906.0 angstrom 3, Z = 4. The crystal structure is isotypic with the monoclinic modification of Fe2(SO4)3, containing two different Fe(III) and three Se(VI) atomic positions. The FeO6 and SeO4 polyhedra are only slightly distorted, the mean Fe - O bond lengths are 1.986 angstrom and 2.004 angstrom, the average distances within the SeO4 tetrahedra are each 1.628 angstrom. The isolated FeO6 octahedra only share corners with SeO4 tetrahedra to build a framework structure.