Cobalt(II) cyanide

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Cobalt(II) cyanide
IUPAC name
Cobalt(II) cyanide
Other names
cobaltous cyanide
3D model (JSmol)
ECHA InfoCard 100.008.028
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 dihydrate
degraded with dissolution by NaCN, KCN, NH4OH, HCl
+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).
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Infobox references

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 has been used as a precursor to cobalt carbonyl.[2]


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

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

Hydrated Co(CN)2 dissolves in the presence of excess potassium cyanide, forming a red solution of K4Co(CN)6. This material further oxidizes to yellow K3Co(CN)6.


  1. ^ Lide, David R., ed. (2006). CRC Handbook of Chemistry and Physics (87th ed.). Boca Raton, FL: CRC Press. ISBN 0-8493-0487-3. 
  2. ^ Heinz W. Sternberg, Irving Wender, Milton Orchin Cobalt Tetracarbonyl Hydride: (Cobalt Hydrocarbonyl) Inorganic Syntheses, 1957, vol. V, p. 192. doi:10.1002/9780470132364.ch55
  3. ^ John H. Bigelow, "Potassium Hexacyanocobaltate(III)" Inorganic Syntheses, 1946, Volume I1, p. 225.