Evidence for Long-Lived Excited States of [CnH2]2+ Carbodications
Appling, J. R.; Shields, G. C.; Moran, T. F. Evidence for Long-Lived Excited States of [CnH2]2+ Carbodications. Org. Mass Spectrom. 1986, 21 (2), 69-75.
The energetics, structures, stabilities and reactivities of[CnH2]2+ ions have been investigated using computational methods and experimental mass spectrometric techniques. Spontaneous decompositions of [CnH2]2+ into [CnH]+ + H+ products, observed for ions with odd-n values, have been explained by invoking the formation of excited triplet states. Even-n [CnH]+ ions possess triplet ground states with low-lying excited states, whereas odd-n ions have triplet states with energies several eV above ground singlet states. Radiationless transitions of vibrationally excited long-lived triplet state ions into singlet state continua are suggested as possible mechanisms for spontaneous deprotonation processes of odd-n [CnH2]2+ ions. Evidence for these long-lived excited states has been obtained in bimolecular single electron transfer reactions.
Organic Mass Spectrometry