Thallous azide, TlN₃

Thallous azide (hydronitride, hydrazoate), TlN₃, is precipitated as a white, crystalline solid when solutions of thallous sulphate or nitrate and sodium azide are mixed. It is sparingly soluble in cold, more readily soluble in hot water, from which it separates on cooling in tetragonal needles (a:c = 1:0.5881) isomorphous with the potassium and rubidium salts. Thallous azide slowly turns brown in sunlight. It melts at 334° in an atmosphere of carbon dioxide, and is reduced to thallium when heated in hydrogen. When suddenly heated or subjected to shock, it explodes.