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

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 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)-λ5-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-λ6-tellanes (trans-PhTeF4OR), thus providing an approach to introduce the functional group into organic molecules.