Reactions of Bifunctional Perfluoroarylsilanes with Activated C-F Bonds in Perfluorinated Arenes.

Reactions of bifunctional perfluoroarylsilanes, p- and m-C6F4(SiMe3)2 as well as o-BrC6F4SiMe3, with substituted perfluoroarenes having electron-withdrawing groups were investigated using NMR and density functional theory calculation techniques. The C-F bond in perfluoroarenes was activated by the para-position of an electron-withdrawing group, such as CF3, C6F5, CN, and NO2. The reaction of C6F4(SiMe3)2 mainly occurred at the para-position of the perfluoroarenes and also occurred at the ortho-position of C6F5CN and C6F5NO2. Two equivalent reactions of perfluoroarenes with bifunctional p- and m-C6F4(SiMe3)2 provided disubstituted perfluoroarenes, along with a small amount of protonated monosubstituted perfluoroarenes. The reaction of o-BrC6F4SiMe3 with the CF3- and CN-substituted pentafluorobenzenes provided unexpected coupling products between C-Br and C-F bonds, in addition to the coupling products between C-SiMe3 and C-F bonds.