A widely varying range of products in reactions of C6F5BrF2, C6F5IF2, and C6F5IF4 with Lewis acids of different strength |
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Authors: | Hermann-Josef Frohn Frank Bailly Vadim V. Bardin |
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Affiliation: | a Inorganic Chemistry, University of Duisburg-Essen, Lotharstr. 1, D-47048 Duisburg, Germany b N.N. Vorozhtsov Novosibirsk Institute of Organic Chemistry, SB RAS, Acad. Lavrentjev Ave. 9, 630090 Novosibirsk, Russia |
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Abstract: | The relative fluoride donor ability: C6F5BrF2 > C6F5IF2 > C6F5IF4 was outlined from reactions with Lewis acids of graduated strength in different solvents. Fluoride abstraction from C6F5HalF2 with BF3·NCCH3 in acetonitrile (donor solvent) led to [C6F5HalF·(NCCH3)n][BF4]. The attempted generation of [C6F5BrF]+ from C6F5BrF2 and anhydrous HF or BF3 in weakly coordinating SO2ClF gave C6F5Br besides bromoperfluorocycloalkenes C6BrF7 and 1-BrC6F9. In reactions of C6F5IF2 with SbF5 in SO2ClF the primary observed intermediate (19F NMR, below 0 °C) was the 4-iodo-1,1,2,3,5,6-hexafluorobenzenium cation, which converted into C6F5I and 1-IC6F9 at 20 °C. The reaction of C6F5IF4 with SbF5 in SO2ClF below −20 °C gave the cation [C6F5IF3]+ which decomposed at 20 °C to C6F5I, 1-iodoperfluorocyclohexene, and iodoperfluorocyclohexane. Principally, the related perfluoroalkyl compound C6F13IF4 showed a different type of products in the fast reaction with AsF5 in CCl3F (−60 °C) which resulted in C6F14. Intermediate and final products of C6F5HalFn−1 (n = 3, 5) with Lewis acids were characterized by NMR in solution. Stable solid products were isolated and analytically characterized. |
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Keywords: | Perfluoroorganobromine(III) difluoride Perfluoroorganoiodine(III) difluoride Perfluoroorganoiodine(V) tetrafluoride Fluoride abstraction Perfluoroorganyl(fluoro)halonium cations NMR spectroscopy |
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