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. This compound is used as a source of singlet oxygen.
Preparation
Potassium peroxochromate is prepared by treating potassium chromate with hydrogen peroxide at 0 °C:
2 CrO2−4 + 8 H2O2 → 2 [Cr(O2)4]2− + 8 H2OThe intermediate tetraperoxochromate(VI) is reduced by hydrogen peroxide, forming tetraperoxochromate(V):34
2 [Cr(O2)4]2− + 2 OH− + H2O2 → 2 [Cr(O2)4]3− + 2 H2O + O2Thus, the overall reaction is:
2 CrO2−4 + 9 H2O2 + 2 OH− → 2 [Cr(O2)4]3− + 10 H2O + O2The compound decomposes spontaneously at higher temperatures.
References
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. /wiki/Bibcode_(identifier) ↩
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. /wiki/Doi_(identifier) ↩
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. https://web.archive.org/web/20110718225714/http://deposit.ddb.de/cgi-bin/dokserv?idn=969592612&dok_var=d1&dok_ext=pdf&fi... ↩
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. https://zenodo.org/record/1426142 ↩