Effective redox reactions by chromium oxide anions: Sulfur dioxide oxidation in the gas phase

Unprecedented redox reactions of chromium oxide anions have been observed in the gas phase and investigated by mass spectrometric techniques and electronic structure calculations. The effective oxi-dizing and reducing power of chromium oxide anions is unravelled by sulfur dioxide: CrO4 and CrO2 generate CrO3 as the reduction and oxidation product, respectively, together with SO3 and SO as the oxidation and reduction products of SO2, respectively. Computations predict that the reactions of CrO4 and CrO2 proceed through rather stable ion-dipole complexes and that CrO4 produces also a strongly bound [CrSO6] - species.