The Highest Oxidation State of Rhodium Rhodium VII in [RhO3]

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 tabl