The structures and energies of C3H2F3+ isomers have been calculated, and at the MP4(SDQ)/6-31G// HF/6-31G + ZPVE level fluorine migration converting CH2=C+CF3 (3) to the allylic cation CH2=CFCF2+ (4) is exothermic by 31.5 kcal/mol, with a barrier involving a bridged fluoronium ion of only 6.1 kcal/mol. Rearrangement of 3 to CHF=CHCF2+ (16) is exothermic by 44.9 kcal/mol and occurs by a multistep process including a 1, 3-fluorine migration with no barrier higher than 0.3 kcal/mol. Comparative studies of C3H6+ are also reported. It is concluded that 3 is a good candidate for an experimental search for fluorine migration in carbocations.
ASJC Scopus subject areas
- Organic Chemistry