Potassium tetraperoxochromate(V)

Potassium peroxochromate, potassium tetraperoxochromate(V), or simply potassium perchromate, is an inorganic chemical 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.[2] This compound is used as a source of singlet oxygen.[1]

Potassium tetraperoxochromate(V)
Identifiers
3D model (JSmol)
ChemSpider
  • InChI=1S/Cr.3K.4O2/c;;;;4*1-2/q+5;3*+1;4*-2
    Key: JSURYJVAXIVWCV-UHFFFAOYSA-N
  • [O-][O-].[O-][O-].[O-][O-].[O-][O-].[K+].[K+].[K+].[Cr+5]
Properties
K
3CrO
8
Molar mass 297.286
Appearance red brown
Melting point 70 °C (158 °F; 343 K)[1] (decomposes)
Poorly soluble (0 °C)
Reacts (45 °C)[1]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Preparation

Potassium peroxochromate is prepared by treating potassium chromate with hydrogen peroxide at 0 ºC:

2 CrO2−
4 + 8 H
2O
2 → 2 [Cr(O
2)
4]2−
 + 8 H
2O

The intermediate tetraperoxochromate(VI) is reduced by hydrogen peroxide, forming tetraperoxochromate(V):[3][4]

2 [Cr(O
2)
4]2−
 + 2 OH−
 + H
2O
2 → 2 [Cr(O
2)
4]3−
 + 2 H
2O + O
2

Thus, the overall reaction is:

2 CrO2−
4 + 9 H
2O
2 + 2 OH−
 → 2 [Cr(O
2)
4]3−
 + 10 H
2O + O
2

The compound decomposes spontaneously at higher temperatures.

References
  1. 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. ACS Publications. 97 (12): 3299–3306. doi:10.1021/ja00845a003.
  2. 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.
  3. Haxhillazi, Gentiana. "Preparation, Structure and Vibrational Spectroscopy of Tetraperoxo Complexes of CrV+, VV+, NbV+ and TaV+". Archived from the original on 2011-07-18. Retrieved 2009-03-07.
  4. Riesenfeld, E. H.; Wohlers, H.E.; Kutsch, W.A. (1905). "Höhere Oxydationsproducte des Chroms". Berichte der Deutschen Chemischen Gesellschaft. 38 (2): 1885–1898. doi:10.1002/cber.190503802113.
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