Oxidative Fluorination of Selenium and Tellurium Compounds using a Thermally Stable Phosphonium SF5- Salt Accessible from SF6

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 SF5- anion and a chemically inert phosphonium cation and is exceptionally thermally stable. Accordingly, it was used to generate the SeF5- and TeF5- anions from the elemental chalcogens and to prepare the unknown tetrafluoro(phenyl)-lambda(5)-selenate PhSeF4- and -tellurate PhTeF4- from the corresponding diphenyl dichalcogenides. In addition, we show that further derivatization of [PhTeF4](-) by oxidation to trans-PhTeF4O- and subsequent alkylation gives access to a new class of trans-(alkoxy)(phenyl)tetrafluoro-lambda(6)-tellanes (trans-PhTeF4OR), thus providing an approach to introduce the functional group into organic molecules.

Automated summary

This paper reports a new oxidative fluorination reagent consisting of an SF5- anion and a chemically inert phosphonium cation, which is thermally stable. Using this reagent, the SeF5- and TeF5- anions were successfully generated and tetrafluoro(phenyl)-lambda(5)-selenate and -tellurate were synthesized. Furthermore, further derivatization of the tetrafluoro(phenyl)-lambda(5)-tellurate allowed the introduction of functional groups into organic molecules.