Generation and assay of C6HxD(7-x) (x = 1-6) benzenium ions. A FA-SIFT study

An experimental study of protonated benzene in the gas phase in reported, stimulated by the recent suggestion of a face centered pi-complex structure as the most stable form of protonated benzene. C6HxD(7-x) ions have been formed either by protonation of C6D6 by H3 O+ and ensuing H/D exchange reactions with H20 or by the mirror isotope reaction of C6D6 with D30+/D20. Their assay by two sampling methods, H+/D+ transfer to strong bases and collisionally activated dissociation, was found consistent with a sigma-complex species