Synthesis and decomposition studies of dialkyltellurides of type RTeR′

Unsymmetrical dialkyltellurides of type RTeR′ suitable for use as precursors in the metalorganic vapour phase epitaxy (MOVPE) of cadmium mercury telluride (CMT) can be prepared by an alkyl exchange process. For certain organotellurium compounds, reaction of R2Te (R = alkyl, allyl) with R′2Te2 (R′ = alkyl) produces an equilibrium mixture containing RTeR′ and RTe2R′. Suitable selection of R and R′ allows good yields of RTeR′ to be prepared in high purity. ESR studies show that free radicals are formed on thermal or photochemical decomposition of R2Te and that the stability of (allyl)TeMe is very similar to that of (allyl)2Te but quite different from that of Me2Te.</p

Homolytic reactions of diorganotellurium and diorganoditellurium compounds in solution; an EPR study

The thermal and photochemical decompositions of dialkyltelluriums and dialkylditelluriums in t-butylbenzene solvent have been studied by, EPR spectroscopy. On photolysis, di-t-butyl, diallyl, allyl methyl, and dibenzyl tellurium showed EPR spectra of t-butyl, allyl, allyl, and benzyl radicals respectively. Alkyl radicals were not detected directly on thermolysis in the range 300-370 K but, primary, secondary, and tertiary alkyl, benzyl and allyl telluriums gave spin adducts of the corresponding alkyl radical with nitrosodurene. Dimethyl tellurium was unreactive in the same temperature range. The rates of thermal decomposition of the diorgano telluriums at 315 K were found to be in the following order, as judged by the intensity of the spin adduct spectra: tBu2Te ∼ tBuTeMe &gt; (allyl)2Te ∼ allylTeMe &gt; sBu2Te &gt; (benzyl)2Te &gt; iPr2Te &gt; Et2Te &gt; Me2Te. For dihex-5-enyltellurium the results were consistent with formation and cyclisation of hex-5-enyl and hex-5-enetelluryl radicals. In the case of dipent-4-enyltellurium, the results suggested that both exo- and endo-cyclisation of the pentene telluryl radicals were important. Di-isopropyl- and di-t-butyl-ditelluriums gave spin adducts of the corresponding alkyl radicals on thermolysis in the same temperature range as the monoalkyltelluriums.</p