Chromium(VI) oxide peroxide

Chromium(VI) oxide peroxide
Other names

chromium(VI) oxide peroxide
Identifiers
Jmol-3D images Image 1
Properties
Molecular formula CrO5
Molar mass 131.99 g mol−1
Solubility in water soluble (decomposes without stabilisers)
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Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Chromium(VI) peroxide (CrO5) or chromium oxide peroxide is an unstable compound formed by the addition of acidified hydrogen peroxide solutions to solutions of chromates, such as sodium chromate. The generally yellow chromates turn to dark blue-brown as chromium(VI) peroxide is formed. The metal chromate reacts with hydrogen peroxide and an acid to give chromium peroxide, water, and the metal salt of the acid.

M2CrO4 + 2 H2O2 + 2 H+ → CrO5 + 3 H2O + 2 M+

After a few seconds, they decompose to turn green as chromium(III) compounds are formed.[1] To avoid this decomposition, it is possible to stabilize chromium(VI) oxide peroxide in diethyl ether by adding a layer of ether above the (bi)chromate solution and shaking during the addition of hydrogen peroxide, so that the chromium(VI) peroxide (unstable in the aqueous phase in which newly formed) is dissolved in ether. In this condition it can be observed over a much longer period.

2 CrO5 + 7 H2O2 + 6 H+ → 2 Cr3+ + 10 H2O + 7 O2

This compound contains one oxo ligand and two peroxo ligands, making a total of five oxygen atoms per chromium atom.

Contents

Derivatives

This compound as the stabilized etherate, bipyridyl and pyridyl complexes have been found to be effective oxidants in organic chemistry.[2] The structure of the pyridyl complex has been determined crystallographically.[3]


Gallery

References

  1. ^ Holleman, Arnold F.; Wiberg, Egon; Wiberg, Nils; (1985). "Chromium" (in German). Lehrbuch der Anorganischen Chemie (91–100 ed.). Walter de Gruyter. pp. 1081–1095. ISBN 3-11-007511-3."
  2. ^ Firouzabadi, H.; Iranpoor, N.; Kiaeezadeh, F.; Toofan, J. (1986). "Chromium(VI) based oxidants-1 Chromium peroxide complexes as versatile, mild, and efficient oxidants in organic synthesis". Tetrahedron 42: 719. doi:10.1016/S0040-4020(01)87476-7. 
  3. ^ Stomberg, Rolf (1962). "Crystal Structure of Peroxochromates, CrO5⋅C5H5N". Nature 196 (4854): 570. doi:10.1038/196570b0. 

External links