Sodium ferrifluoride, Na₃FeF₆

Sodium ferrifluoride, Na₃FeF₆, is obtained on adding ferric chloride or fluoride to a neutral solution of sodium fluoride. It is formed as a white, crystalline precipitate, which is only sparingly soluble in water. It does not give a red colour with thiocyanates, thus indicating that the iron atom is part of the negative radicle.

The subhydrate, 2Na₃FeF₆.H₂O, has also been obtained.

Sodium fluoride and ferric fluoride yield a eutectic mixture, melting at 892° C. and corresponding in composition to the formula 65 NaF.35FeF₃.