Abstract: | The NO2C7H6]+ ions generated from m-alkylnitrobenzenes have been shown to be different in their decomposition from those generated from p-alkylnitrobenzenes, even when the alkyl group is methyl and the departing fragment a hydrogen radical. Thus, in these cases even molecular ions of relatively high internal energy do not reversibly ring-expand to cycloheptatriene structures. In addition, the NO2C7H6]+ ions, assumed to be benzylic, do not ring-expand to nitrotropylium ions at internal energies sufficient to cause subsequent loss of NO or NO2 from the p- and m-isomers, respectively. |