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
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.008.028
UNII
  • 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
  • [Co+2].[C-]#N.[C-]#N
Properties
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)
insoluble[1]
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).
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 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 KnCo(CN)2+n though it is disputed whether n=3 or 4.[4] This material further oxidizes to yellow hexacyanocobaltate(III), which can be isolated as the salt K3Co(CN)6.

The solid is a coordination polymer 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.[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]

References
  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. Sternberg, Heinz W.; Wender, Irving; Orchin, Milton; Lynch Jr., M. A.; Sesny, W. J. (1957). "Cobalt Tetracarbonyl Hydride". Inorganic Syntheses. Inorganic Syntheses. Vol. 5. pp. 192–195. doi:10.1002/9780470132364.ch55. ISBN 9780470132364.
  3. Bigelow, John H.; Bailar Jr., John C. (1946). "Potassium Hexacyanocobaltate(III)". Inorganic Syntheses. Inorganic Syntheses. Vol. 2. pp. 225–227. doi:10.1002/9780470132333.ch72. ISBN 9780470132333.
  4. Adamson, Arthur W. (1951). "Exchange Studies with Complex Ions. III. The Nature of the Complex Formed between Cobalt(II) and Potassium Cyanide, and its Exchange with Radiocyanide Ion in Aqueous Solution". J. Am. Chem. Soc. 73 (12): 5710–5713. doi:10.1021/ja01156a063.
  5. Weiss, Armin; Rothenstein, W. (1963). "Cobalt(II) Cyanide, its Three-Demensional Frame-work Structure and Zeolitic Compounds". Angewandte Chemie International Edition. 2 (7): 396. doi:10.1002/anie.196303962.


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