Catalyzed Radical Termination in the Presence of Tellanyl Radicals

The decomposition of the diazo initiator dimethyl 2,2′‐azobis(isobutyrate) (V‐601), generating the Me 2 C . (CO 2 Me) radical, affords essentially the same fraction of disproportionation and combination in media with a large range of viscosity (C 6 D 6 , [D 6 ]DMSO, and PEG 200) in the 25–100 °C range. This is in stark contrast to recent results by Yamago et al. on the same radical generated from Me 2 C(TeMe)(CO 2 Me) and on other X‐TeR systems (X=polymer chain or unimer model; R=Me, Ph). The discrepancy is rationalized on the basis of an unprecedented RTe . ‐catalyzed radical disproportionation, with support from DFT calculations and photochemicaL V‐601 decomposition in the presence of Te 2 Ph 2 .