Cobalt(II) cyanide

  1. Home
  2. Wiki
Cobalt(II) cyanide
Names
IUPAC name
Cobalt(II) cyanide
Other names
cobaltous cyanide
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.008.028 Edit this at Wikidata
UNII
  • InChI=1S/2CN.Co/c2*1-2;/q2*-1;+2 checkY
    Key: CWZOMTYLSNXUEL-UHFFFAOYSA-N checkY
  • 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
Appearance deep-blue powder
hygroscopic
Density 1.872 g/cm3 (anhydrous)
Melting point 220 °C (428 °F; 493 K) (decomposes)
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 checkY☒N ?)

Cobalt(II) cyanide is the inorganic compound with the empirical formula Co(CN)2 and structural formula Co3[Co(CN)5]2. It is a coordination polymer that has attracted intermittent attention over many years in the area of inorganic synthesis and homogeneous catalysis.[2] The anhydrous and octahydrate forms are both blue solids insoluble in water. A red trihydrate has also been reported,[3] but this was later shown to be an oxidized form containing the ion [Co(CO)5(O2)]3–.[4][5][6][7]

Uses

[edit]

Cobalt(II) cyanide has been used as a precursor to dicobalt octacarbonyl.[8]

Preparation and structure

[edit]

The octahydrate form is prepared by the reaction between tetraethylammonium pentacyanocobaltate and cobalt(II) chloride under oxygen-free conditions:[4]

2 (Et4N)3[Co(CN)5] + 3 Co(H2O)6Cl2 → [Co(H2O)6]3[Co(CN)5]2 · 2H2O↓ + 6 Et4N+ + 6 Cl−

Heating of the octahydrate at 100 °C produces the anhydrous form.[4] The anhydrous form can also be prepared from the reaction of cobalt(II) bromide and potassium cyanide or sodium cyanide in liquid ammonia, then heating the resulting ammoniate to 210 °C in ethyl benzoate.[9]

The oxidized form containing the ion [Co(CO)5(O2)]3– is obtained as a reddish-brown precipitate by adding two equivalents of potassium cyanide to a cobalt salt solution.[10] With excess cyanide, the red-brown solid dissolves to give pentacyanocobaltate, which can oxidize in the presence of oxygen to hexacyanocobaltate(III).[2][7]

Solid cobalt(II) cyanide is a coordination polymer consisting of Co2+ and [Co(CN)5]3- (pentacyanocobaltate) ions.[4]

References

[edit]
  1. ^ Lide, David R., ed. (2006). CRC Handbook of Chemistry and Physics (87th ed.). Boca Raton, Florida: CRC Press. ISBN 0-8493-0487-3.
  2. ^ a b Kwiatek, Jack (1968). "Reactions Catalyzed by Pentacyanocobaltate(II)". Catalysis Reviews. 1: 37–72. doi:10.1080/01614946808064700.
  3. ^ 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.
  4. ^ a b c d Beauvais, Laurance G.; Long, Jeffrey R. (2002-10-01). "Co 3 [Co(CN) 5 ] 2 : A Microporous Magnet with an Ordering Temperature of 38 K". Journal of the American Chemical Society. 124 (41): 12096–12097. doi:10.1021/ja027768z. ISSN 0002-7863. Retrieved 2025-06-22.
  5. ^ Brown, Leo D.; Raymond, Kenneth N. (1975-11-01). ".sigma.-Bonded dioxygen adduct of the pentacyanocobaltate(II) anion. Crystal structure of tris(tetraethylammonium)dioxopentacyanocobaltate(II) pentahydrate". Inorganic Chemistry. 14 (11): 2595–2601. doi:10.1021/ic50153a003. ISSN 0020-1669. Retrieved 2025-06-22.
  6. ^ White, D. A.; Solodar, A. J.; Baizer, M. M. (1972). "Tetraalkylammonium pentacyanocobaltates. Their preparation, properties, and reactivity". Inorganic Chemistry. 11 (9): 2160–2167. doi:10.1021/ic50115a034. ISSN 0020-1669. Retrieved 2025-06-22.
  7. ^ a b Poskozim, Paul S. (1969). "The preparation of potassium hexacyanocobaltate(III)". Journal of Chemical Education. 46 (6): 384. doi:10.1021/ed046p384. ISSN 0021-9584. Retrieved 2025-06-22.
  8. ^ 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. {{cite book}}: ISBN / Date incompatibility (help)
  9. ^ Mosha, D. M. S. J. Chem. Soc. Pak. 1985, 7, 173.
  10. ^ 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. {{cite book}}: ISBN / Date incompatibility (help)


Stub icon

This inorganic compound–related article is a stub. You can help Wikipedia by expanding it.