Nickel Nitrite, Ni(NO₂)₂

A solution of Nickel Nitrite, Ni(NO₂)₂, is obtained by double decomposition of nickel sulphate and barium nitrite, but the salt itself has not been isolated. It yields a stable double salt with potassium nitrite, namely, 4KNO₂.Ni(NO₂)₂, which crystallises in brownish red octahedra, when excess of potassium nitrite is added to a concentrated solution of nickel nitrite. In the presence of a calcium salt a yellow crystalline precipitate is obtained, of composition represented by the formula 2KNO₂.Ca(NO₂)₂.2Ni(NO₂)₂ or K₂CaNi(NO₂)₆, which closely resembles potassium cobalti-nitrite in appearance. The corresponding barium and strontium salts have been prepared.