Abstract
By reaction of AlEt₃ with less than 3 equiv of HORF (RF = C(CF₃)₃) the ethylaluminum sesquialkoxide (Et)₂Al(μ-ORF)₂Al(Et)(ORF) (1a; NMR, XRD) can be obtained. As a univalent electronegative residue, the perfluorinated alkoxy moieties can be seen as pseudohalides. In this respect, 1a represents the closest approximation to the hitherto unknown crystal structure of the alkylaluminum sesquihalide Al₂R₃X₃. By further reaction of 1a with HORF, the Lewis superacid Al(ORF)₃ is formed, which reacts with Me₃SiCl to give Me₃Si–Cl–Al(ORF)₃ (2a; NMR, XRD, IR, Raman). 2a can be used for further reactions as prepared but slowly decomposes at ca. 0 °C to give the known Me₃Si–F–Al(ORF)₃ (2b) and several byproducts. The observed decomposition products, combined with quantum chemical calculations, provide evidence for an even higher silylating potential of 2a over that of 2b.