CATALYTIC-OXIDATION OF THE (HYDROXYMETHYL)CHROMIUM(III) ION BY THE SUPEROXOCHROMIUM(III) ION

The superoxochromium(III) ion, CrO22+, is an efficient catalyst for autoxidation of the (hydroxymethyl)chromium(III) ion, CrCH2OH2+, in aqueous solution. The reaction involves one-electron oxidation of CrCH2OH2+ by CrO22+, k = 137 M-1 s-1, to yield Cr2+, CH2O, and the novel (hydroperoxo)chromium(III) ion, CrO2H2+. The Cr2+ produced reacts rapidly with O2 to regenerate the catalyst, CrO22+. When oxygen is depleted, the Cr2+ reacts instead with CrO22+ to produce the chromyl(IV) ion, CrO2+. This initiates a chain reaction that rapidly consumes the remaining CrO22+ and a stoichiometric amount of CrCH2OH2+.