Evidence of HF Loss in C or C- + C6FxH6-x (1 ≤ x ≤ 5) Reactions.

Patterns of anions produced by passing benzene and fluorobenzenes through a photoemission ion source show evidence of carbon addition with subsequent -H or HF loss. We recently reported a study of the fulvenallenyl structures of C7FxH5-x - (0 ≤ x ≤ 2) formed in the former reaction. In this follow-up study, we report the anion PE spectra of the C7FxH4-x- (0 ≤ x ≤ 4) anions. We present experimental evidence that HF loss is necessary for C7FxH4-x- (0 ≤ x ≤ 4) formation, and calculations predict the reactions to be thermodynamically favorable. Based on a comparison between the experimental spectra and computational results on the anion and neutral, we conclude that two distinct C7FxH4-x- structures are formed. One structure resembles a fulvenallenyl structure that has undergone deprotonation from the acetylenic group, and the other is a cumulenic or other chain structure. The former is more stable than the latter except in the case of C7F4-. Results of calculations suggest that the cumulenic structure becomes increasingly stable with fluorination.