Abstract
Fluorinated group 16 moieties are attractive building blocks in synthetic chemistry but only few synthetic methods are available to prepare them. Herein, we report a new oxidative fluorination reagent capable of stabilizing reactive fluorinated anions. It consists of an SF(5) (-) anion and a chemically inert phosphonium cation and is exceptionally thermally stable. Accordingly, it was used to generate the SeF(5) (-) and TeF(5) (-) anions from the elemental chalcogens and to prepare the unknown tetrafluoro(phenyl)-λ(5) -selenate PhSeF(4) (-) and -tellurate PhTeF(4) (-) from the corresponding diphenyl dichalcogenides. In addition, we show that further derivatization of [PhTeF(4) ](-) by oxidation to trans-PhTeF(4) O(-) and subsequent alkylation gives access to a new class of trans-(alkoxy)(phenyl)tetrafluoro-λ(6) -tellanes (trans-PhTeF(4) OR), thus providing an approach to introduce the functional group into organic molecules.