Antimony Oxybromides

Two oxybromides have been described: antimonyl bromide, SbOBr, obtained by the action of light and air upon a solution of antimony tribromide in carbon disulphide, and Sb₄O₅Br₂, obtained either by hydrolysis of antimony tribromide, or by heating together antimony tribromide and absolute alcohol in a sealed tube. Antimonyl bromide is a brownish powder (the colour possibly being due to impurities) which on heating separates into two other substances. Continued heating converts it entirely into antimony trioxide. The compound Sb₄O₅Br₂ may be obtained in the form of monoclinic crystals, or as a white powder, which decomposes on heating, yielding antimony tribromide and antimony trioxide.

While antimony tetrabromide does not appear to have been isolated, a complex compound of this substance with ammonium bromide has been obtained by adding successively bromine and ammonium bromide to a solution of antimony tribromide in hydrobromic acid. It forms black octahedra of composition corresponding to (NH₄)₂SbBr₆. The rubidium salt, Rb₂SbBr₆, has also been obtained, in the form of black, pointed, hygroscopic prisms. It is decomposed by water.