2O ₆(F)] ? ? ]]>

摘要

>Two gas-phase catalytic cycles involving C–F bond activation of trifluoroethanol and trifluoroacetic acid were detected by multistage mass spectrometry experiments. A binuclear dimolybdate centre [Mo₂O₆(F)]?acts as the catalyst in each cycle. The first cycle, entered via the reaction of [Mo₂O₆(OH)]?with trifluoroethanol and elimination of water to form [Mo₂O₆(OCH₂CF₃)]?, proceeds via four steps: (1) oxidation of the alkoxo ligand and its elimination as aldehyde; (2) reaction of [Mo₂O₅(OH)]?with trifluoroethanol and elimination of water to form [Mo₂O₅(OCH₂CF₃)]; (3) decomposition of the alkoxo ligand via loss of 1,1 difluoroethene; and (4) reaction of [Mo₂O₆(F)]?with a second equivalent of trifluoroethanol to regenerate Mo₂O₆(OCH₂CF₃)]?. Steps (2) and (3) do not occur at room temperature and require collisional activation to proceed. The second cycle is entered via the reaction of [Mo₂O₆(OH)]?with trifluoroacetic acid and elimination of water to form [Mo₂O₆(O₂CCF₃)]?and involves two steps only: (1) fluoride transfer to a molybdenum centre to form [Mo₂O₆(F)]?; (2) reaction of [Mo₂O₆(F)]?with trifluoroacetic acid and loss of water to regenerate [Mo₂O₆(O₂CCF₃)]?. Comparisons are made with the chemistry of [Mo₂O₆(OH)]?reacting with acetic acid.]]>