Reactions of Doubly Ionized Benzene with Nitrogen and Water: A Nitrogen‐Mediated Entry into Superacid Chemistry

Even in the highly diluted gas phase, rather than electron transfer the benzene dication C 6 H 6 2+ undergoes association with dinitrogen to form a transient C 6 H 6 N 2 2+ dication which is best described as a ring‐protonated phenyl diazonium ion. Isotopic labeling studies, photoionization experiments using synchrotron radiation, and quantum chemical computations fully support the formation of protonated diazonium, which is in turn a prototype species of superacidic chemistry in solution. Additionally, reactions of C 6 H 6 2+ with background water involve the transient formation of diprotonated phenol and, among other things, afford a long‐lived C 6 H 6 OH 2 2+ dication, which is attributed to the hydration product of Hogeveen’s elusive pyramidal structure of C 6 H 6 2+ , as the global minimum of doubly ionized benzene. Nitrogen is essential for the formation of the C 6 H 6 OH 2 2+ dication in that it mediates the formation of the water adduct, while the bimolecular encounter of the C 6 H 6 2+ dication with water only leads to (dissociative) electron transfer.