Generation of neutrals from anionic precursors in the gas phase: the anionic, neutral and cationic rearrangements of CCCCHO and CCCHCO to HCCCCO

Copyright © 2003 Elsevier Science B.V. All rights reserved.The anions, neutrals and cations of the isomers HCCCCO, CCCHCO and CCCCHO have been studied by experiment and by theory at the CCSD(T)/aug-cc-pVDZ//B3LYP/6-31G(d) level of theory. Anions have been synthesised from precursor neutrals in the source of a mass spectrometer. The anion [HCCCCO]- and (a major proportion of) [CCCHCO]- retain their bond connectivity when energised, but theoretical calculations predict that singlet [CCCCHO]- rearranges to singlet [CCCHCO]- over a barrier of only 28kJmol-1. However, triplet [CCCCHO]- is stable under these conditions. Neutralisation/reionisation of [HCCCCO]- results in the sequential two-electron vertical oxidation [HCCCCO]-→HCCCCO→[HCCCCO]+, with the doublet neutral being stable for the microsecond duration of the NR experiment. In contrast, neutralisation of [CCCHCO]- and [CCCCHO]- yield HCCCCO in rearrangements which occur during or subsequent to neutralisation of the anions. Two-electron oxidation (charge reversal, -CR+) of [CCCHCO]- and [CCCCHO]- both produce the rearranged cation [HCCCCO]+ in exothermic reactions. © 2003 Elsevier Science B.V. All rights reserved.Mark Fitzgerald, Suresh Dua, John H. Bowie, and Andrew M. McAnoyhttp://www.elsevier.com/wps/find/journaldescription.cws_home/500847/description#descriptio