Potassium Ruthenium Nitrite, 4KNO₂.2Ru(NO₂)₃

Potassium Ruthenium Nitrite, 4KNO₂.2Ru(NO₂)₃, is prepared by adding potassium nitrite to a dilute, acidified solution of ruthenium chloride at 60° C. until the solution just becomes alkaline. On concentrating slowly in the cold, orange-red crystals are obtained. With hydrochloric acid a nitroso derivative is obtained, whilst ammonium chloride decomposes it with evolution of nitrogen.

A basic salt, 8KNO₂.Ru₂O.(NO₂)₄, has also been isolated.