SYNTHESES AND MECHANISTIC STUDIES OF SYMMETRICAL TETRAORGANYLTELLURIUM(IV) (R4TE) AND DIORGANYLTELLURIUM(II) (R'2TE) COMPOUNDS (R = R' = ME, NORMAL-BU, ME3SICH2, AND CH2=CH-R' = TERT-BU AND ALLYL)

Tetraorganyltellurium(IV) compounds (R4Te, R = Me, n-Bu, Me3SiCH2, and CH2 = CH) have been prepared by the reaction of TeCl4 with 4 equiv of LiR or RMgX. Decomposition of the R4Te compounds led to the formation of the symmetric diorganyltellurium(II) compounds (R2Te). Me4Te and (Me3SiCH2)4Te thermally and photolytically decomposed by a free-radical pathway. (CH2 = CH)4Te decomposed by noncoupling reductive elimination. While (t-Bu)2Te and (allyl)2Te have also been prepared by the reaction of TeCl4 with 4 equiv of (t-Bu)Li or (allyl)MgCl, respectively, their corresponding R4Te intermediates could not be isolated. (t-Bu)2Te was also isolated as a minor product from the reaction of (t-Bu)TeLi with (t-Bu)I in THF. (Allyl)2Te was prepared by the reaction of Li2Te with 2 equiv of (allyl)I in THF. These compounds have been characterized by H-1, C-13, and Te-125 NMR spectroscopies.