Te(C6H4-4-CF3)(6) 1a was obtained by the unique one-pot reaction of LiC6H4-4-CF3 with TeCl4. The Te atom resides in the highest oxidation state (Te-VI) having six C-Te bonds in 1a. Compound 1a is extremely thermally stable and not light sensitive unlike tetraorganotellurium compounds. The X-ray crystallographic analysis of 1a revealed a rare example of approximately T-h molecular symmetry. (C) 1997 Elsevier Science Ltd.
Cleavage of Tellurium-Carbon Bonds of Hexavalent Organotellurium Compounds by Potassium Graphite
The potassium ion intercalated in graphite results in unique reactivity of Ar5 Te- K+ C8 (1), formed by cleavage of one of the Te-C(Ar) bonds of Ar6 Te by KC8 . Thus, 1 reacted quantitatively with CH3 I to give Ar5 TeCH3 , which was not obtainable from Ar5 Te- Li+ . The Te-CH3 bond of Ar5 TeCH3 is cleaved in preference to the Te-C(Ar) bonds, and formation of Ar4 Te(CD3 )2 suggests the intermediacy of the hypervalent dianion Ar4 Te2- .
(4-CF3C6H4)4(CH3)TeX [X=Cl (trans-7a-Cl) and X=Br (trans-7a-Br)] were synthesized by the following methods: 1) one-potsynthesis of 1 a, 2) the reaction of SO2Cl2 or Br2 with Ar5Te(-)Li+ generated from TeCl4 or TeBr4 with five equivalents of ArLi, 3) reductive cleavage of Ar(6-m)(CH3)(m)Te (m=0 or 2) with KC8 followed by treatment with CH3I, 4) valence expansion reaction from low-valent tellurium compounds