Synthesis, Characterization, and Application of Two Al(ORF)3 Lewis Superacids

We report herein the synthesis and full characterization of the donor-free Lewis superacids Al(ORF)3 with ORF=OC(CF3)3 (1) and OC(C5F10)C6F5 (2), the stabilization of 1 as adducts with the very weak Lewis bases PhF, 1,2-F2C6H4, and SO2, as well as the internal C?F activation pathway of 1 leading to Al2(F)(ORF)5 (4) and trimeric [FAl(ORF)2]3 (5, ORF=OC(CF3)3). Insights have been gained from NMR studies, single-crystal structure determinations, and DFT calculations. The usefulness of these Lewis acids for halide abstractions has been demonstrated by reactions with trityl chloride (NMR; crystal structures). The trityl salts allow the introduction of new, heteroleptic weakly coordinating [Cl-Al(ORF)3]- anions, for example, by hydride or alkyl abstraction reactions.