K_2AuPS_4, Tl_2AuPS_4, K_2AuAsS_4, and KAu_5P_2S_8: Syntheses, Structures, and Properties of Quaternary Gold Thiophosphate and Thioarsenate Compounds

摘要

The novel compounds K_2AuPS_4 (1), Tl_2AuPS_4 (2), K_2AuAsS_4 (3), and KAu_5P_2S_8 (4) have been synthesized by direct reaction of the elements with a molten alkaline polythiophosphate(arsenate) flux at 550 ℃. The crystal structures of these compounds have been determined by single-crystal X-ray diffraction techniques. 1, 2, and 3 crystallize in the monoclinic space group P2_1/m. The structures of 1, 2, and 3 consist of infinite, one-dimensional anionic chains running along the crystallographic b axis. The chains are separated by potassium or thallium ions. Neighbouring Au atoms are bridged by MS_4~(3-) tetrahedra (M = P, As) in trans orientation. Compound 4 crystallizes in the space group P2_1/c. The anionic chains of 4 are built up from linear AuS_2 dumbbell units and PS_4~(3-) tetrahedra. The chains extend along the [110] and [110] direction and are separated by charge balancing K~+ cations. Each of the compounds was investigated by differential thermal analysis, FT-IR, and solid-state UV/Vis diffuse reflectance spectroscopy.