Thallium nitride, Tl₃N

Thallium nitride, Tl₃N, is obtained as a black precipitate when liquid ammonia solutions of thallous nitrate and potassium amide are mixed: -

3TlNO₃ + 3KNH₂ = Tl₃N + 3KNO₃ + 2NH₃.

It dissolves in a liquid ammonia solution of ammonium nitrate, re-forming thallous nitrate: -

Tl₃N + 3NH₄.NO₃ = 3TlNO₃ + 4NH₃,

and also dissolves when excess of potassium amide is added. The latter solution when evaporated at -40° deposits yellow crystals of potassium amide and dipotassium ammonothallite, TlNK₂.4NH₃, a compound which dissociates at 20° in vacuum, leaving the compound TlNK₂.2NH₃.