Structural diversity by mixing chalcogen atoms in the chalcophosphate system K/In/P/Q (Q = S, Se)

The new thiophosphate salt K4In2(PS4)2(P2S6) (1), the selenophosphate salts K5In3(μ3-Se)(P2Se6)3 (2), K4In4(μ-Se)2(P2Se6)3 (3), and the mixed seleno-/thiophosphate salt K4In4(μ-Se)(P2S2.36Se3.64)3 (4) are described. For the first time, a structurally different outcome of a chalcophosphate reaction was observed when sulfur and selenium are mixed, for example, by the use of K2S/P2Se5/S/In instead of K2Se/P2Se5/Se/In or K2S/P2S5/S/In. In compounds 1-4 indium atoms exist in a variety coordination environments. While in 1, indium is octahedrally coordinated, in 2-4 tetrahedral, trigonal-bipyramidal, and octahedral coordination environments are found for indium atoms. This remarkable structural diversity possibly is a reason, why particularly indium chalcophosphate flux reactions often produce a large variety of compounds at intermediate temperatures. In the mixed seleno-/thiophosphate salt K4In4(μ-Se)(P2S2.36Se3.64)3 (4) most of the chalcogen sites around the tetrahedrally coordinated P atoms show mixed S/Se occupancy. There is, however, a preference for Se binding to In ions and S binding to potassium ions.