da Silva Santos, M.; Medel, R.; Flach, M.; Ablyasova, O.S.; Timm, M.; von Issendorff, B.; Hirsch, K.; Zamudio-Bayer, V.; Riedel, S.; Lau, J.T.: Exposing the Oxygen-Centered Radical Character of the Tetraoxido Ruthenium(VIII) Cation [RuO4]+. ChemPhysChem 24 (2023), p. e202300390/1-7
10.1002/cphc.202300390
Open Access Version
Abstract:
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]+.