Long‐Lived Radical Cations of Monocyclic Arenes at Room Temperature Obtained by NbF5 Acting as an Oxidizing Agent and Counterion Precursor

Salt of the earth: Radical cation salts of monocyclic arenes, including benzene, have been obtained in a reaction where niobium pentafluoride behaves both as an oxidizing agent (conversion into NbF4) and fluoride acceptor (to afford the counterion [Nb2F11]−, see picture). Anion–π-electron density interactions, as revealed by experimental and computational studies, are crucial in providing unprecedented inertness to the radical cations.