Cobalt(II) cyanide is the
inorganic compound
In chemistry, an inorganic compound is typically a chemical compound that lacks carbon–hydrogen bonds, that is, a compound that is not an organic compound. The study of inorganic compounds is a subfield of chemistry known as '' inorganic chemist ...
with the formula Co(CN)
2. It is
coordination polymer
A coordination polymer is an inorganic or organometallic polymer structure containing metal cation centers linked by ligands. More formally a coordination polymer is a coordination compound with repeating coordination entities extending in 1, 2, o ...
that has attracted intermittent attention over many years in the area of inorganic synthesis and
homogeneous catalysis.
Uses
Cobalt(II) cyanide has been used as a precursor to
dicobalt octacarbonyl
Dicobalt octacarbonyl is an organocobalt compound with composition . This metal carbonyl is used as a reagent and catalyst in organometallic chemistry and organic synthesis, and is central to much known organocobalt chemistry. It is the parent me ...
.
Preparation and structure
The trihydrate salt is obtained as a reddish-brown precipitate by adding
potassium cyanide
Potassium cyanide is a compound with the formula KCN. This colorless crystalline salt, similar in appearance to sugar, is highly soluble in water. Most KCN is used in gold mining, organic synthesis, and electroplating. Smaller applications includ ...
to a cobalt salt solution:
:CoCl
2(H
2O)
6 + 2 KCN → Co(CN)
2 + 2 KCl + 6 H
2O
Hydrated Co(CN)
2 dissolves in the presence of excess potassium cyanide, forming a red solution of K
''n''Co(CN)
2+''n'' though it is disputed whether ''n''=3 or 4.
This material further oxidizes to yellow hexacyanocobaltate(III), which can be isolated as the salt K
3Co(CN)
6.
The solid is a
coordination polymer
A coordination polymer is an inorganic or organometallic polymer structure containing metal cation centers linked by ligands. More formally a coordination polymer is a coordination compound with repeating coordination entities extending in 1, 2, o ...
consisting of cobalt atoms linked by cyanide units in a cubic arrangement, each such cobalt atom having
octahedral geometry, and an additional cobalt atom in half of the cubic cavities.
That is, the structure is actually Co
o(CN)3sub>2 in a
zeolite
Zeolites are microporous, crystalline aluminosilicate materials commonly used as commercial adsorbents and catalysts. They mainly consist of silicon, aluminium, oxygen, and have the general formula ･y where is either a metal ion or H+. These pos ...
-like structure. It forms hydrates and other inclusion complexes by having substances diffuse into the cavities that do not contain the cobalt atoms.
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References
Cobalt(II) compounds
Cyanides
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