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 > (allyl)₂Te ∼ allylTeMe > ^sBu₂Te > (benzyl)₂Te > ⁱPr₂Te > Et₂Te > 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.