Bismuth Thiobromide, BiSBr

Bismuth Thiobromide, BiSBr, has been obtained by heating together a mixture of bismuth tribromide and sulphur. It may be obtained more readily by the action of hydrogen sulphide on bismuth tribromide, or by the action of bromine upon dried, precipitated bismuth trisulphide. In each case the action must be carefully regulated. The former reaction, when carried out at temperatures up to a very low red heat, may be represented by the equation

BiBr₃ + H₂S = BiSBr + 2HBr

while at full red heat the following occurs:

2BiBr₃ + 3H₂S = Bi₂S₃ + 6HBr

The second reaction is carried out at a low red heat, and may be represented by the equation

Bi₂S₃ + 2Br₂ = BiSBr + BiBr₃ + 2S