Preparation, characterisation and reactions of tellurocarbonyl difluoride and trifluoromethanetellurenyl iodide

Abstract

With the synthesis of TeCF₂ the first telluroketone has been isolated. Two different types of preparation are described. In the first Hg(TeCF₃)₂ is treated with Et₂All to give low yields of TeCF₂. In the second method TeCF₂ is prepared via pyrolysis of the novel compound Me₃SnTeCF₃ at 280 °C with yields of 50–60%. Preparation by this method has made it possible to obtain the IR spectra of TeCF₂ in the gas phase and in an argon matrix, as well as its mass spectrum. The compound reacts with SeCF₂ to give [graphic omitted]F₂ and undergoes a cycloaddition reaction with 2,3-dimethylbutadiene. It is thermally very unstable: on warming its cyclic dimer is formed quantitatively. This reacts with BX₃(X = Cl or Br) to give the corresponding chlorinated and brominated 1,3-ditelluretanes. Dissolution of these in dimethylformamide yields complexes with the solvent. In the initially described method for the generation of TeCF₂, CF₃Tel·I₂ is also formed as a by-product. An alternative route to this compound involves the formation of CF₃Tel in solution by reactions of CF₃TeTeCF₃ with I₂. On cooling to –70 °C, the corresponding I₂ adduct is precipitated. The existence of CF₃Tel has been proven by its reaction with Hg(SeCF₃)₂ and Hg(NSO)₂, yielding the novel compounds CF₃SeTeCF₃ and CF₃TeNSO, respectively.