Barium Amide, Ba(NH₂)₂

If barium be heated in a current of dry ammonia at 200° C., barium amide, or baramide, Ba(NH₂)₂, is obtained as a greyish-white mass. It darkens and liquefies at 280° C., and becomes green at 340° C. At higher temperatures, 460° C. in dry ammonia, or 430° C. in vacuo, it decomposes with formation of the nitride which, when heated in ammonia at 400° C., is partially reconverted into the amide.

If the compound of barium bromide with ammonia, BaBr₂.8NH₃, is left in contact with potassium ammonium for two or three days, hydrogen is evolved and barium amide and potassium bromide are left. The latter is removed by liquid ammonia.

BaBr₂ + 2NH₃K = Ba(NH₂)₂ + 2KBr + H₂.

Barium amide is also formed as a white precipitate by the action of potassamide on an excess of a barium salt in liquid' ammonia solution.

An amide of the composition Ba₃(NH₂)₂ has been obtained by the absorption of hydrogen by barium nitride. It is less stable than the corresponding calcium and strontium compounds, and reacts readily with a further quantity of hydrogen at low temperatures to give the hydride and nitrogen, a certain amount of ammonia being also evolved.

By pouring a solution of a barium salt in liquid ammonia into excess of a solution of potassamide, a microcrystalline precipitate of potassium ammonobarate, BaNK.2NH₃, or Ba(NH₂)₂.KNH₂, is formed, similar to potassium ammonocalciate and strontianate. It is unchanged by heating to 100° C. It is insoluble in liquid ammonia, but is decomposed and dissolved in liquid ammonia solutions of ammonium nitrate. Water readily hydrolyses it into potassium and barium hydroxides and ammonia.