A widely varying range of products in reactions of C 6F 5BrF 2, C 6F 5IF 2, and C 6F 5IF 4 with Lewis acids of different strength

Abstract

The relative fluoride donor ability: C 6F 5BrF 2 > C 6F 5IF 2 > C 6F 5IF 4 was outlined from reactions with Lewis acids of graduated strength in different solvents. Fluoride abstraction from C 6F 5HalF 2 with BF 3·NCCH 3 in acetonitrile (donor solvent) led to [C 6F 5HalF·(NCCH 3) n ][BF 4]. The attempted generation of [C 6F 5BrF] + from C 6F 5BrF 2 and anhydrous HF or BF 3 in weakly coordinating SO 2ClF gave C 6F 5Br besides bromoperfluorocycloalkenes C 6BrF 7 and 1-BrC 6F 9. In reactions of C 6F 5IF 2 with SbF 5 in SO 2ClF the primary observed intermediate ( 19F NMR, below 0 °C) was the 4-iodo-1,1,2,3,5,6-hexafluorobenzenium cation, which converted into C 6F 5I and 1-IC 6F 9 at 20 °C. The reaction of C 6F 5IF 4 with SbF 5 in SO 2ClF below −20 °C gave the cation [C 6F 5IF 3] + which decomposed at 20 °C to C 6F 5I, 1-iodoperfluorocyclohexene, and iodoperfluorocyclohexane. Principally, the related perfluoroalkyl compound C 6F 13IF 4 showed a different type of products in the fast reaction with AsF 5 in CCl 3F (−60 °C) which resulted in C 6F 14. Intermediate and final products of C 6F 5HalF n−1 ( n = 3, 5) with Lewis acids were characterized by NMR in solution. Stable solid products were isolated and analytically characterized.