Antimony Thioiodide, SbSI

Antimony Thioiodide, SbSI, is obtained by the action of antimony trisulphide on antimony triiodide, by the action of iodine upon antimony trisulphide, or by the action of hydrogen sulphide upon antimony triiodide heated to 150° C. It crystallises in small, dark red, lustrous, needle-shaped crystals of a form similar to those of kermesite. It melts at 392° C. and above this temperature decomposes forming a mixture of trisulphide and triiodide. It is not decomposed by hot or cold water, or by dilute acids. Hydrogen sulphide is set free by the action of concentrated hydrochloric acid; sulphur and iodine by the action of concentrated nitric acid. Alkali hydroxides and carbonates remove iodine, leaving a residue of thioantimonites.

Several antimony iodocyanides have been obtained. By heating mercuric cyanide and antimony triiodide in dry xylene, mercuric antimony iodocyanide, Hg[SbI₃(CN)₂], is obtained. Further heating results in the formation of trimercuric antimony iodocyanide, Hg₃[Sb₂I₆(CN)₆]; while the corresponding cuprous compound, Cu₆[Sb₂I₆(CN)₆], is obtained in a similar manner.