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.