da Silva Santos, M.; Medel, R.; Kruse, S.; Flach, M.; Ablyasova, O.S.; Timm, M.; von Issendorff, B.; Hirsch, K.; Zamudio-Bayer, V.; Riedel, S.; Lau, J. T.: Direct Spectroscopic Confirmation of the Oxygen-Centered Diradical Character of the Tetraoxidorhenium(VII) Cation [Re(O)4]+. Chemistry Methods 4 (2024), p. e202400023/1-8
10.1002/cmtd.202400023
Open Accesn Version
Abstract:
Mononuclear inorganic diradical species are scarce. Here, we confirm, via X-ray absorption spectroscopy in the gas phase combined with computational studies, the oxygen-centered diradical character of the tetraoxidorhenium(VII) cation. A dioxido-superoxido isomer, close in energy to the diradical, is also found, where rhenium appears in its rare oxidation state of +6. Addition of one or two hydrogen atoms to [Re,O4]+ forms hydroxido ligands, and strongly disfavors isomers with any oxygen-oxygen bond. This adds spectroscopic characterization of the rhenium oxidation state and the nature of ligands to the known ability of [Re,O4]+ to perform two consecutive hydrogen-atom abstraction reactions from methane, and demonstrates that pentaatomic [Re,O4]+ combines a metal center in its highest oxidation state with two oxygen-centered radical ligands in a highly reactive species.