Exposing the Oxygen‐Centered Radical Character of Tetraoxido Ruthenium(VIII) Cation, [RuO4]+
Mayara da Silva Santos, Robert Medel, Max Flach, Olesya S. Ablyasova, Martin Timm, Bernd von Issendorff, Konstantin Hirsch, Vicente Zamudio-Bayer, Sebastian Riedel, J. Tobias Lau- Physical and Theoretical Chemistry
- Atomic and Molecular Physics, and Optics
The tetraoxido ruthenium(VIII) radical cation, [RuO4]+, should be a strong oxidizing agent, but has been difficult to produce and investigate so far. In our X‐ray absorption spectroscopy study, in combination with quantum‐chemical calculations, we show that [RuO4]+, produced via oxidation of ruthenium cations by ozone in the gas phase, forms the oxygen‐centered radical ground state. The oxygen‐centered radical character of [RuO4]+ is identified by the chemical shift at the ruthenium M3 edge, indicative of ruthenium(VIII), and by the presence of a characteristic low‐energy transition at the oxygen K edge, involving an oxygen‐centered singly‐occupied molecular orbital, which is suppressed when the oxygen‐centered radical is quenched by hydrogenation of [RuO4]+ to the closed‐shell [RuO4H]+ ion. Hydrogen‐atom abstraction from methane is calculated to be only slightly less exothermic for [RuO4]+ than for [OsO4]+.