Boron imide, B₂(NH)₃

Boron imide, B₂(NH)₃, is best prepared by heating the compound B₂S₃.6NH₃ at 115° to 120° in a rapid stream of ammonia for some days: -

B₂S₃.6NH₃ = B₂(NH)₃ + 3NH₄.SH.

Boron imide is a light, white powder, insoluble in alcohol, ether, carbon disulphide, and liquid ammonia. It begins to decompose at 125° to 130° with the evolution of ammonia, and at a slightly higher temperature is completely resolved into, boron nitride and ammonia. When boiled with water, boron imide is decomposed into ammonia and boric acid.

Boron imide is a feebly basic compound, and when added to liquid hydrogen chloride it forms a white hydrochloride, B₂(NH)₃.3HCl, insoluble in organic media, and decomposed by heat or water.