The reactivity of perfluoroaryltellurium(IV) dihalides towards cyanide, crystal structures of (C6F5)3TeCl and C6F5TeTeC6F5

The reactivity of R2TeHal2 (R=C6F5, 4-CF3C6F4; Hal=F, Cl, Br) towards AgCN and Me3SiCN was examined. The perfluoroaryl substituted tellurium(IV) difluorides reacted with AgCN and Me3SiCN to give the tellurium(IV) dicyanides (C6F5)2Te(CN)2 (1) and (CF3C6F4)2Te(CN)2 (2). Treatment of the corresponding tellurium dichlorides and tellurium dibromides with AgCN and Me3SiCN did not result in the formation of 1 and 2. Performing the reaction in a haloform as solvent gave the tris(perfluoroaryl)telluronium halides (C6F5)3TeCl (3), (C6F5)3TeBr (4), (CF3C6F4)3TeCl (5) and (CF3C6F4)3TeBr (6), whereas the counter ion of the telluronium ion depended on the used solvent, CHCl3 or CHBr3. All new compounds were investigated by analytical and spectroscopic methods. The constitution of 3–6 was confirmed by the determination of the crystal structure of 3. The reaction of C6F5Li with I2 led mainly to the monotelluride (C6F5)2Te and gave the hoped-for ditelluride C6F5TeTeC6F5 (7) only as a by-product. The crystal structure of 7 was determined.