TRIFLUOROTELLUROACETYL FLUORIDE, ITS CYCLIC DIMER AND PRECURSORS - PREPARATION, CHARACTERIZATION AND REACTIVITY

With the synthesis of CF3(F)C=Te, the second, non-resonance stabilised perfluorinated telluracarbonyl has been isolated and characterised by gas-phase IR and mass spectrometry. It was prepared via pyrolysis of the novel compound Me(3)SnTeC(2)F(5) at 500 degrees C, 10(-3) Torr in 40-50% yield. The compound CF3(F)C=Te is only stable at -196 degrees C and dimerises quantitatively a few degrees above this temperature to the corresponding mixture of bis(trifluoromethyl)-2,4-difluoro-1,3-dit elluranes which cannot be separated by physical nor chemical procedure s. Their reaction with BX(3)(X = Cl or Br) yielded chlorinated and bro minated cis/trans-1,3-ditelluretanes. Additionally the telluracarbonyl undergoes a cycloaddition reaction with 2,3-dimethylbutadiene forming ,6-dihydro-4,5-dimethyl-2-trifluoromethyltellurin. The required precu sors for the synthesis of the perfluorinated telluracarbonyls Te(2)R(2 ) and Te(2)R(2) were prepared by three different methods. The compound s Me(3)SnTeR [R = C2F5 or (CF3)(2)CF] were obtained from Te-x(C2F5)(2) (x = 1 or 2) or Te[(CF3)(2)CF](2) and Me(3)SnH in good yield.