Cobalt(II) cyanide

Cobalt(II) cyanide is the inorganic compound with the formula Co(CN)₂. It is coordination polymer that has attracted intermittent attention over many years in the area of inorganic synthesis and homogeneous catalysis.

Cobalt(II) cyanide

Names
IUPAC name Cobalt(II) cyanide
Other names cobaltous cyanide
Identifiers
CAS Number	542-84-7 Y 20427-11-6 (dihydrate) N 26292-31-9 (trihydrate) N
3D model (JSmol)	Interactive image
ChemSpider	61631 Y
ECHA InfoCard	100.008.028
PubChem CID	68336
UNII	3300OC3VVZ Y
CompTox Dashboard (EPA)	DTXSID20969165
InChI InChI=1S/2CN.Co/c2*1-2;/q2*-1;+2 Y Key: CWZOMTYLSNXUEL-UHFFFAOYSA-N Y InChI=1/2CN.Co/c2*1-2;/q2*-1;+2 Key: CWZOMTYLSNXUEL-UHFFFAOYAR
SMILES [Co+2].[C-]#N.[C-]#N
Properties
Chemical formula	Co(CN)2
Molar mass	110.968 g/mol (anhydrous) 147.00 g/mol (dihydrate) 165.02 g/mol (trihydrate)
Appearance	deep-blue powder hygroscopic (anhydrous) reddish-brown powder (dihydrate)
Density	1.872 g/cm3 (anhydrous)
Melting point	280 °C (536 °F; 553 K) (anhydrous)
Solubility in water	insoluble[1]
Solubility	dihydrate degraded with dissolution by NaCN, KCN, NH4OH, HCl
Magnetic susceptibility (χ)	+3825·10−6 cm3/mol
Related compounds
Other anions	Cadmium chloride, Cadmium iodide
Other cations	Zinc cyanide, Calcium cyanide, Magnesium cyanide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). N verify (what is YN ?) Infobox references

Uses

Cobalt(II) cyanide has been used as a precursor to dicobalt octacarbonyl.^[2]

Preparation and structure

The trihydrate salt is obtained as a reddish-brown precipitate by adding two equivalents of potassium cyanide to a cobalt salt solution:^[3]

CoCl₂(H₂O)₆ + 2 KCN → Co(CN)₂ + 2 KCl + 6 H₂O

With excess cyanide, the red brown dicyanide dissolves to give pentacyanocobaltate.^[4]

Solid cobalt(II) cyanide is a coordination polymer consisting of cobalt ions 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.^[5] That is, the structure is actually Co[Co(CN)₃]₂ in a zeolite-like structure. It forms hydrates and other inclusion complexes by having substances diffuse into the cavities that do not contain the cobalt atoms.^[5]