Triniobium Pentanitride, Nb₃N₃

Triniobium Pentanitride, Nb₃N₃, has been obtained by the action of ammonia gas on an ether solution of niobium pentachloride, but it is most conveniently prepared synthetically. Finely powdered niobium is subjected to prolonged heating at about 1000° C. in an atmosphere of pure, dry nitrogen. It is a black powder which is stable in the air. On being heated in air it glows and forms the pentoxide, but it is not oxidised by lead chromate even at high temperatures. It is not attacked by boiling water, hydrochloric, nitric or sulphuric acids. Boiling caustic potash solutions are also without action on it, but molten caustic potash decomposes it with the evolution of ammonia.

Other nitrides of niobium of doubtful composition have been obtained by the action of ammonia on niobium pentoxide, niobium oxychloride and niobium pentachloride.