Synthesis, Characterization, and Application of Two Al(OR super(F)) sub(3) Lewis Superacids

We report herein the synthesis and full characterization of the donor-free Lewis superacids Al(OR super(F)) sub(3) with OR super(F)=OC(CF sub(3)) sub(3) (1) and OC(C sub(5)F sub(10))C sub( 6)F sub(5) (2), the stabilization of 1 as adducts with the very weak Lewis bases PhF, 1,2-F sub(2)C sub(6)H sub(4 ), and SO sub(2), as well as the internal C--F activation pathway of 1 leading to Al sub(2)(F)(OR super(F)) sub(5) (4) and trimeric [FAl(OR super(F)) sub(2)] sub(3) (5, OR super(F)=OC(CF sub(3)) sub(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(OR super(F)) sub(3)] super(-) anions, for example, by hydride or alkyl abstraction reactions. A super method! The synthesis of the donor-free Lewis superacids Al(OR super(F)) sub(3) with OR super(F)=OC(CF sub(3)) sub(3) (1) and OC(C sub(5)F sub(10))C sub( 6)F sub(5) (2), as well as stabilization of 1 with the very weak Lewis bases PhF, 1,2-F sub(2)C sub(6)H sub(4 ), and SO sub(2), is reported (see figure). Applications of 1 and 2 in bond heterolysis reactions with Cl--CPh sub(3) giving the trityl cation and the respective weakly coordinating anion [ClAl(OR super(F)) sub(3)] super(-) are also described.