Potassium tetraperoxochromate(V)

Potassium tetraperoxochromate(V)

Identifiers
CAS Number	12331-76-9
Properties
Chemical formula	K 3CrO 8
Molar mass	297.286
Appearance	red brown
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

Potassium peroxochromate, or potassium tetraperoxochromate(V), is an inorganic chemical having the chemical formula K₃[Cr(O₂)₄]. A crystalline ionic solid with a brown color, it is the potassium salt of tetraperoxochromate(V), one of the few examples of chromium in the +5 oxidation state.^[1]

Preparation

Potassium peroxochromate is prepared by reacting hydrogen peroxide with potassium chromate at low temperatures:

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):^[2][3]

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. 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.
2. Haxhillazi, Gentiana. "Preparation, Structure and Vibrational Spectroscopy of Tetraperoxo Complexes of Cr^V+, V^V+, Nb^V+ and Ta^V+".
3. Riesenfeld, E. H.; Wohlers, H.E.; Kutsch, W.A. (1905). "Höhere Oxydationsproducte des Chroms". Chemische Berichte der Deutschen Chemischen Gesellschaft 38: 1885–1898. doi:10.1002/cber.190503802113.