Ferricyanide
{{Short description|Anion in which a Fe3+ ion is complexed by 6 CN− ions}}
{{Distinguish|ferrocyanide}}
{{Chembox
|Watchedfields = changed
|verifiedrevid = 444964110
|ImageFile = HexacyanidoferratIII_2.svg
|ImageClass = skin-invert-image
|ImageSize = 175
|ImageFile1 = Ferricyanide-3D.png
|ImageClass1 = bg-transparent
|ImageSize1 = 240
|IUPACName = iron(3+) hexacyanide
|SystematicName = hexacyanidoferrate(III)
|OtherNames =ferric hexacyanide; hexacyanidoferrate(3−); hexacyanoferrate(III)
|Section1 = {{Chembox Identifiers
|CASNo_Ref = {{cascite|correct|CAS}}
|CASNo = 13408-62-3
|ChEBI = 5020
|KEGG = C00324
|PubChem = 439210
|ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
|ChemSpiderID = 388349
|SMILES = N#C[Fe-3](C#N)(C#N)(C#N)(C#N)C#N
|StdInChI=1S/6CN.Fe/c6*1-2;/q6*-1;+3
|StdInChIKey = YAGKRVSRTSUGEY-UHFFFAOYSA-N
}}
|Section2 = {{Chembox Properties
|Formula = [Fe(CN)6]3−
}}
|Section8 = {{Chembox Related
|OtherCompounds=Ferrocyanide
|OtherCations=Hexacyanonickelate(III)
}}
}}
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.{{Ullmann |author1=Gail, E. |author2=Gos, S. |author3=Kulzer, R. |author4=Lorösch, J. |author5=Rubo, A. |author6=Sauer, M. |author7=Kellens, R. |author8=Reddy, J. |author9=Steier, N. |author10=Hasenpusch, W. | title = Cyano Compounds, Inorganic |date=October 2011 | doi = 10.1002/14356007.a08_159.pub3 }}
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 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
References
{{Reflist}}
{{Cyanides}}