Potassium hexacyanochromate(III)
(K+)3[Cr(CN)6]3− | |
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| IUPAC name
Potassium hexacyanochromate(III) | |
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| ECHA InfoCard | 100.033.694 |
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| MeSH | Hexacyanochromate |
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CompTox Dashboard (EPA) |
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| Properties | |
| C6CrK3N6 | |
| Molar mass | 325.399 g·mol−1 |
| Appearance | Vivid, yellow, opaque crystals |
| Density | 1.71 g/cm3 |
| 30.96 g/100 mL (20 °C) | |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references | |
Potassium hexacyanochromate(III) is an inorganic compound with the formula K3[Cr(CN)6]. It consists of three potassium cations and [Cr(CN)6]3− anion. It is a yellow, air-stable, paramagnetic solid.[1] It is isomorphous with potassium ferricyanide.
Synthesis
The salt was reported in 1800's, but early preparations started with Cr(III) salts, which are poor precursors.[2] It is readily prepared by cyanation of chromium(II) compounds, such as chromous acetate, followed by an oxidation step:</sup[3]
- [Cr2(OAc)4] + 12 KCN → 2 K4[Cr(CN)6] + 4 KOAc (OAc- = acetate)
- 4 K4[Cr(CN)6] + O2 + 2 H2O → 4 K3[Cr(CN)6] + 4 KOH
The procedure exploits the lability of Cr(II) salts and their easy oxidation to give the exchange-inert Cr(III) derivative.
Reactions
Reduction of hexacyanochromate(III) gives the Cr(II) and Cr(0) derivatives, [Cr(CN)6]4- and [Cr(CN)6]6-, respectively.[4]
The hexacyanochromate(III) anion serves as a ligand towards other metal electrophiles.
References
- ↑ F. Hein; S. Herzog. "Potassium Hexacyanochromate (III)". In G. Brauer (ed.). Handbook of Preparative Inorganic Chemistry. Vol. 2 (2 ed.). p. 1373.
- ↑ Cruser, Frederick Van Dyke; Miller, Edmund H. (1906). "The Insoluble Chromicyanides". J. Am. Chem. Soc. 28 (9): 1132–51. doi:10.1021/ja01975a003.
- ↑ Marvaud, Valérie; Mallah, Talal; Verdaguer, Michel (2004). Potassium Hexacyanochromate(III) and Its 13C-Enriched Analog. Inorganic Syntheses. Vol. 34. p. 144. doi:10.1002/0471653683.ch4.
- ↑ Eaton, Janice P.; Nicholls, David (1981). "The Complex Cyanides of Chromium(II) and Chromium(0)". Transition Metal Chemistry. 6 (4): 203–206. doi:10.1007/BF00618223. S2CID 96193332.