Silicobromoform, SiHBr₃

Silicobromoform (Tribromosilicane), SiHBr₃, is formed similarly to silicochloroform by the action of hydrogen bromide on crude silicon prepared from silica and magnesium, and is freed from the tetrabromide by fractional distillation. Silicobromoform is a colourless liquid which boils at 115°-117° C. (Gattermann or 109°-111° C. (Besson) (CHBr₃ boils at 151° C.); it does not solidify at -60° C.

Its vapour ignites spontaneously in the air; and the liquid reacts with water, forming, when kept cool, silicoformic anhydride. Silicobromoform appears to form additive compounds with ammonia and phosphine.

According to von Mahn pentabromosilico ethane, Si₂HBr₅, is formed by the interaction of silicane and bromine, and forms colourless needles which melt at 89° C., the boiling-point of the liquid being 230° C.