Cobalt(II) cyanide
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| IUPAC name
Cobalt(II) cyanide
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| Other names
cobaltous cyanide
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| Identifiers | |
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3D model (JSmol)
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| ChemSpider | |
| ECHA InfoCard | 100.008.028 |
PubChem CID
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| UNII | |
CompTox Dashboard (EPA)
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| 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
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Cadmium chloride, Cadmium iodide |
Other cations
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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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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 areas of inorganic synthesis and homogeneous catalysis.[2] The anhydrous and octahydrate forms are both blue solids insoluble in water.
Preparation and structure
[edit]The octahydrate is prepared by the reaction between tetraethylammonium pentacyanocobaltate and cobalt(II) chloride:[3]
- 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.[3] 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.[4]
The structural formula Co3[Co(CN)5]2 shows that cobalt(II) cyanide consists of Co2+ and [Co(CN)5]3– (pentacyanocobaltate) ions,[3] the latter of which also has cobalt in its +2 oxidation state.
Oxygenation and redox
[edit]A red trihydrated has also been reported,[5] but this was later shown to be the oxygenated derivative containing the ion [Co(CN)5(O2)]3–.[6][7][8]
The oxygenated derivative is obtained as a reddish-brown precipitate by adding two equivalents of potassium cyanide to a solution of cobalt(II) salts in air.[9] With excess cyanide, the red-brown solid dissolves to give pentacyanocobaltate, which oxidizes in the presence of oxygen to hexacyanocobaltate(III).[2][8]
Uses
[edit]Cobalt(II) cyanide has been used as a precursor to dicobalt octacarbonyl.[10]
References
[edit]- ^ Lide, David R., ed. (2006). CRC Handbook of Chemistry and Physics (87th ed.). Boca Raton, Florida: CRC Press. ISBN 0-8493-0487-3.
- ^ a b Kwiatek, Jack (1968). "Reactions Catalyzed by Pentacyanocobaltate(II)". Catalysis Reviews. 1: 37–72. doi:10.1080/01614946808064700.
- ^ a b c Beauvais, Laurance G.; Long, Jeffrey R. (2002-10-01). "Co3[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.
- ^ Mosha, D. M. S. J. Chem. Soc. Pak. 1985, 7, 173.
- ^ 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.
- ^ 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.
- ^ 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.
- ^ 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.
- ^ 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) - ^ 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)
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