Matrix isolation and DFT calculations of the TMM radical cation generated via the single electron oxidation of a methylenecyclopropane

A γ-irradiation of 2,2-diphenyl-1-methylenecyclopropane (3) in a degassed n-butyl chloride glassy matrix at 77 K produced an intense UV/vis absorption band with λab at 432 nm. This result and calculations based on density functional theory for its radical cation 3+ and the corresponding trimethylenemethane radical cation (2+) strongly suggest that a single electron oxidation of 3 followed by ready ring opening affords 2+, whose molecular geometry is largely twisted (θ = 44.0°), and the positive charge and spin are localized mainly in the diphenyl methyl and allyl moieties, respectively.