Generation and reactivity of vinyltelluryl radical.

Vinyltelluryl radical was prepared by high-vacuum flash pyrolysis from the corresponding divinylditelluride and trapped in an argon matrix at 10 K. The title compound was characterized by IR and UV/Vis spectroscopy, and all experimental data match well with density functional theory at the UB3LYP/def2-QZVPP level. According to UB3LYP/def2-QZVPP computations, the spin density is mainly localized on the Te atom. The vinylogy principle for the vinyltelluryl radical is not applicable due to the lack of delocalization of spin density. Upon irradiation of the matrix with light ( = 365 nm), the vinyltelluryl radical rearranges to a H-Te˙⋯acetylene complex. Doping the matrix with molecular oxygen leads to the hitherto unknown vinyltelluro peroxy radical. The latter isomerizes to the more thermodynamically stable vinyltelluroyl radical by irradiation with light at = 523 nm.