Generation of Perfluoropolyphenylene Oligomers via Carbon−Fluorine Bond Activation by Cp₂Zr(C₆F₅)₂:  A Dual Mechanism Involving a Radical Chain and Release of Tetrafluorobenzyne

Abstract

The thermal decomposition of Cp 2 Zr(C 6 F 5 ) 2 in THF results in the slow formation of Cp 2 Zr(C 6 F 5 )F and tetrafluorobenzyne. The tetrafluorobenzyne is trapped by THF to give several products. The same reaction performed in the presence of durene or furan also results in the formation of Cp 2 Zr(C 6 F 5 )F and the respective Diels−Alder adducts of tetrafluorobenzyne. If Cp 2 Zr(C 6 F 5 ) 2 is heated in the presence of C 6 F 6, linear chains of perfluoroarenes are rapidly generated along with Cp 2 Zr(C 6 F 5 )F. The disappearance of Cp 2 Zr(C 6 F 5 ) 2 is observed to slow dramatically after 30−80% completion, with the extent of reaction being inversely dependent on the concentration of C 6 F 6 . Dual mechanisms involving a rapid radical chain- and a slower tetrafluorobenzyne-producing reaction are proposed to account for these observations.