Te:CF2 (I), the first telluroketone, has been isolated. Hg(TeCF3)2 was treated with Et2AlI to give low yields of I. In a second method I was prepd. via pyrolysis of the novel compd. Me3SnTeCF3 (prepn. given) at 280 Deg with yields of 50-60%. Prepn. by this method has made it possible to obtain IR spectra of I (in the gas phase and in an argon matrix) as well as its mass spectrum. I reacts with SeCF2 to give selenatelluretane II and undergoes a cycloaddn. reaction with 2,3-dimethylbutadiene. I is thermally very unstable: on warming its cyclic dimer is formed quant. The latter reacts with BX3 (X = Cl or Br) to give the corresponding chlorinated and brominated 1,3-ditelluretanes. Dissoln. of these in DMF yields complexes with the solvent. In the initially described method for the generation of I, CF3TeI.I2 was formed as a byproduct. An alternative route to this compd. involves the formation of CF3TeI in soln. by reactions of CF3TeTeCF3 with I2. On cooling to - 70 Deg, the corresponding I2 adduct was pptd. The existence of CF3TeI has been proven by its reaction with Hg(SeCF3)2 and Hg(NSO)2, yielding the novel compds. CF3SeTeCF3 and CF3TeNSO, resp.