C–F Bond Cleavage Reactions with Beryllium, Magnesium, Gallium, Hafnium, and Thorium Halides

Abstract

The work describes unexpected stoichiometric C–F bond cleavage reactions of beryllium, magnesium, gallium, hafnium and thorium halides with α,α,α-trifluorotoluene. The reaction of BeBr2 / GaBr3 or MgBr2 / GaBr3 mixtures as well as neat GaI3 with α,α,α-trifluorotoluene in the presence of (OSi2Me4)2 (I) yields the carbenium ion containing compounds [Ph-C(O2Si2Me4)][GaX4] (X = Br: 1, X = I/F: 2). Both compounds were successfully characterized and a defluorination type reaction under incorporation of a siloxy unit was observed. Compound 1 was also characterized by single-crystal X-ray diffraction analysis. The conversion of α,α,α-trifluorotoluene with BeI2, HfI4 or ThI4 turned out to be a halodefluorination-type reaction with formation of α,α,α-triiodotoluene (3). An adequate NMR spectroscopic and the X-ray crystallographic characterization of 3 were performed for the first time.