Ferricyanide

Not to be confused with ferrocyanide.

Ferricyanide is the name of 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]

Ferricyanide

Names
IUPAC name iron(3+) hexacyanide
Systematic IUPAC name hexacyanidoferrate(III)
Other names ferric hexacyanide; hexacyanidoferrate(3−); hexacyanoferrate(III)
Identifiers
CAS Number	13408-62-3 Y
3D model (JSmol)	Interactive image
ChEBI	CHEBI:5020
ChemSpider	388349 Y
KEGG	C00324
PubChem CID	439210
CompTox Dashboard (EPA)	DTXSID70894190
InChI InChI=1S/6CN.Fe/c6*1-2;/q6*-1;+3 Key: YAGKRVSRTSUGEY-UHFFFAOYSA-N
SMILES N#C[Fe-3](C#N)(C#N)(C#N)(C#N)C#N
Properties
Chemical formula	[Fe(CN)6]3−
Related compounds
Other cations	Hexacyanonickelate(III)
Related compounds	Ferrocyanide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Y verify (what is YN ?) Infobox references

Properties

[Fe(CN)₆]³⁻ consists of a Fe³⁺ center bound in octahedral geometry to six cyanide ligands. The complex has O_h 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 main group cyanides like potassium cyanide, ferricyanides are much less toxic because of the strong bond between the cyanide ion (CN⁻) and the Fe³⁺. They do react with mineral acids, however, to release highly toxic hydrogen cyanide gas.

Uses

Treatment of ferricyanide with iron(II) salts affords the brilliant, long-lasting pigment Prussian blue, the traditional color of blueprints.

See also

• Potassium ferricyanide
• Ferrocyanide