• da Silva Santos, M.; Stüker, T.; Flach, M.; Ablyasova, O.S.; Timm, M.; von Issendorff, B.; Hirsch, K.; Zamudio-Bayer, V.; Riedel, S.; Lau, J.T.: The Highest Oxidation State of Rhodium: Rhodium(VII) in [RhO3]+. Angewandte Chemie - International Edition 61 (2022), p. e202207688/1-5

10.1002/anie.202207688
Open Access Version

Abstract:
Although the highest possible oxidation states of all transition elements are rare, they are not only of fundamental interest but also relevant as potentially strong oxidizing agents. In general, the highest oxidation states are found in the electron-rich late transition elements of groups 7–9 of the periodic table. Rhodium is the first element of the 4d transition metal series for which the highest known oxidation state does not equal its group number of 9, but reaches only a significantly lower value of +6 in exceptional cases. Higher oxidation states of rhodium have remained elusive so far. In a combined mass spectrometry, X-ray absorption spectroscopy, and quantum-chemical study of gas-phaseurn:x-wiley:14337851:media:anie202207688:anie202207688-math-0001 (n=1–4), we identify urn:x-wiley:14337851:media:anie202207688:anie202207688-math-0002 as the urn:x-wiley:14337851:media:anie202207688:anie202207688-math-0003 trioxidorhodium(VII) cation, the first chemical species to contain rhodium in the +7 oxidation state, which is the third-highest oxidation state experimentally verified among all elements in the periodic table.