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Ferricyanide

Anion in which a Fe3+ ion is complexed by 6 CN– ions From Wikipedia, the free encyclopedia

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]

Quick facts Names, Identifiers ...
Ferricyanide
Names
IUPAC name
iron(3+) hexacyanide
Systematic IUPAC name
hexacyanidoferrate(III)
Other names
  • Ferric hexacyanide
  • Hexacyanidoferrate(3−)
  • Hexacyanoferrate(III)
Identifiers
3D model (JSmol)
ChEBI
ChemSpider
KEGG
UNII
  • InChI=1S/6CN.Fe/c6*1-2;/q6*-1;+3
    Key: YAGKRVSRTSUGEY-UHFFFAOYSA-N
  • N#C[Fe-3](C#N)(C#N)(C#N)(C#N)C#N
Properties
[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).
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Properties

[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 main group cyanides like potassium cyanide, ferricyanides are 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 pigment Prussian blue, the traditional color of blueprints.

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