Refinement of the Crystal Structure of Synthetic ThAsS4*

The crystal structure of a synthetic sulfosalt, TlsAsS4, has been refined. The crystal is orthorhombic with space group Pnma .. Four formula units are contained in a unit cell of dimensions a = 0.8893(3), b = 1.0868(5) and c = 0.9088(3) nm. The final R-value is 0.04 for 759 observed reflections. The Tl(l) has seven nearest S atoms with a mean Tl-S bond length of 0.329 nm. Tl(2) has five nearest S atoms with a mean Tl-S bond length of 0.318 nm. The Tl coordination polyhedra form a three-dimensional framework. The As atom has a tetrahedral coordination by four S atoms at a mean distance of 0.216 nm. The AsS4 tetrahedra are isolated.