Potassium tetraperoxochromate(V)
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| IUPAC name
Potassium tetraperoxochromate(V)
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Other names
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3D model (JSmol)
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PubChem CID
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CompTox Dashboard (EPA)
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| Properties | |
| K3[Cr(O2)4] | |
| Molar mass | 297.286 g/mol |
| Appearance | red-brown crystals[1] |
| Melting point | 70 °C (158 °F; 343 K)[2] (decomposes) |
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Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Potassium peroxochromate, potassium tetraperoxochromate(V), or simply potassium perchromate, is an inorganic compound having the chemical formula K3[Cr(O2)4]. It is a red-brown paramagnetic solid. It is the potassium salt of tetraperoxochromate(V), one of the few examples of chromium in the +5 oxidation state and one of the rare examples of a complex stabilized only by peroxide ligands.[3] This compound is used as a source of singlet oxygen.[2]
Preparation
Potassium peroxochromate is prepared starting from chromium trioxide (CrO3), excess potassium hydroxide (KOH), and 30% hydrogen peroxide (H2O2)[4]:
- 2 KOH + CrO3 → K2CrO4 + H2O
Hydrogen peroxide is added at temperatures below −5 °C (23 °F; 268 K)[4]:
- 2 K2CrO4 + 8 H2O2 → 2 K2[Cr(O2)4] + 8 H2O
The intermediate tetraperoxochromate(VI) is reduced by hydrogen peroxide, forming tetraperoxochromate(V)[4]:
- 2 K2[Cr(O2)4] + 2 KOH → 2 K3[Cr(O2)4] + H2O2
Thus, the overall reaction is[4]:
- 2 K2CrO4 + 7 H2O2 + 2 KOH → 2 K3[Cr(O2)4] + 8 H2O
The compound decomposes spontaneously at higher temperatures but may be stored in sealed containers for extended periods.[2][1]
References
- ^ a b Hein, F.; Herzog, S. (1963). "24. Chromium, molybdenum, tungsten, uranium". In G. Brauer (ed.). Handbook of Preparative Inorganic Chemistry, 2nd Ed. Vol. 2. NY, NY: Academic Press. pp. 1391–2.
- ^ a b c d John W. Peters; Paul J. Bekowies; Arthur M. Winer; James N. Pitts Jr. (1975). "Potassium perchromate as a source of singlet oxygen". Journal of the American Chemical Society. 97 (12). ACS Publications: 3299–3306. doi:10.1021/ja00845a003.
- ^ Sergienko, V. S. (2007). "Structural chemistry of peroxo compounds of group VI transition metals: I. Peroxo complexes of chromium". Crystallography Reports. 52 (4): 639–646. Bibcode:2007CryRp..52..639S. doi:10.1134/S1063774507040116. S2CID 95018505.
- ^ a b c d Haxhillazi, Gentiana (2003-11-04). Preparation, Structure and Vibrational Spectroscopy of Tetraperoxo Complexes of CrV+, VV+, NbV+ and TaV+ (Dr. rer. nat. thesis). Siegen, Deutschland: Universität Siegen. urn:nbn:de:hbz:467-523. Archived from the original on 2011-07-18. Retrieved 2009-03-07.