Étude structurale de Tl4SnSe4

The compound Tl4SnSe4 was obtained during the study of pseudobinary SnSe2Tl2Se. It crystallizes in the monoclinic system, space group P2 1 c with unit cell dimensions: a = 8.481(2) A, b = 8.411(2) A, c= 15.800(5) A, β = 102.39(2)°. The unit cell contains four formula units. Densities, dobs. and dcalc. are 7.52 and 7.56, respectively. The crystal structure was determined from 720 reflections collected with a Nonius CAD4 automatic diffractometer using MoKα radiation. The final R value is 0.069. The structure is built up from isolated SnSe4 tetrahedra stabilized by thallium atoms occupying four independent positions. The thallium coordination polyhedra are slightly different from those observed in Tl4SnS4 with which Tl4SnSe4 is isotypic.