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HexacyanidoferratIII 2.svg
PubChem 439210
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Molecular formula C6N6Fe
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
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Ferricyanide is the anion [Fe(CN)6]3−.  It is also called hexacyanoferrate(III) and in rare, but systematic nomenclature, hexacyanidoferrate(III). The most common salt of this anion is potassium ferricyanide, a red crystalline material that is used as an oxidant in organic chemistry.[1]


[Fe(CN)6]3− consists of a Fe3+ center bound in octahedral geometry to six cyanide ligands. The complex has Oh symmetry. The iron is low spin and easily reduced to the related ferrocyanide ion [Fe(CN)6]4−, which is a ferrous (Fe2+) derivative. This redox couple is reversible and entails no making or breaking of Fe-C bonds:

[Fe(CN)6]3− + e → [Fe(CN)6]4−

This redox couple is a standard in electrochemistry.

Compared to normal cyanides like potassium cyanide, ferricyanides are much less toxic because of the tight hold of the CN to the Fe3+. They do react with mineral acids, however, to release highly toxic hydrogen cyanide gas.


Treatment of ferricyanide with ferrous salts affords the brilliant, long-lasting pigment Prussian blue, the traditional color of blueprints.


  1. ^ Gail, E.; Gos, S.; Kulzer, R.; Lorösch, J.; Rubo, A.; Sauer, M.; Kellens, R.; Reddy, J.; Steier, N.; Hasenpusch, W. (October 2011). "Cyano Compounds, Inorganic". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a08_159.pub3. 

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