Formation of Organoxenon Dications in the Reactions of Xenon withDications Derived from Toluene

The bimolecular reactivity of xenon with C7Hn2+ dications (n=6-8), generated by double ionization of toluene using both electrons and synchrotron radiation, is studied by means of a triple-quadrupole mass spectrometer. Under these experimental conditions, the formation of the organoxenon dications C7H6Xe2+ and C7H7Xe2+ is observed to occur by termolecular collisional stabilization. Detailed experimental and theoretical studies show that the formation of C7H6Xe2++H-2 from doubly ionized toluene (C7H82+) and xenon occurs as a slightly endothermic, direct substitution of dihydrogen by the rare gas with an expansion to a seven-membered ring structure as the crucial step. For the most stable isomer of C7H6Xe2+, an adduct between the cycloheptatrienyldiene dication and xenon, the computed binding energy of 1.36 eV reaches the strength of (weak) covalent bonds. Accordingly, electrophiles derived from carbenes might be particularly promising candidates in the search for new rare-gas compounds.