THALLIUM(I) SELENATE

Tl2SeO4 belongs to the beta-K2SO4 family; the asymmetric unit consists of a tetrahedral selenate anion and two Tl cations. Tl(1) and Tl(2) a re surrounded by eleven and nine O atoms respectively. The six O atoms closest to Tl(2) form an irregular octahedron with Tl(2)-O distances of 2.83(2)-3.04(2) angstrom. The TI(1) cation makes short contacts wit h two pairs of symmetrically equivalent O atoms at distances of 3.08(2 ) and 3.082(3) angstrom, respectively, and an even shorter contact [2. 66 (2) angstrom] with a fifth O atom. These five O atoms are on one si de of the TI(1) atom. This irregular coordination may indicate stereoc hemical activity of the Tl(1) lone pair. The environments of the Tl at oms in the present compound are very similar to those in Tl2CrO4.