Electron spin resonance study of radicals in γ-irradiated mono- and poly-cyclic olefins. Part III. Allyl and pentadienyl radicals from dienes and trienes with strained ring structures

Abstract

An e.s.r. study of the radicals produced by low temperature γ-irradiation of dicyclopentadiene and 1-isopropylidenetetrahydroindene in an adamantane–thiourea matrix leads to the identification of the species dicyclopentadien-9-yl (II) and 1-(tetrahydroinden-1-ylidene)ethyl (I) respectively. The origin, structure, and e.s.r. properties of these radicals are discussed on the basis of the results of progressive thermal annealing experiments and of SCF MO calculations performed to the INDO and HMO (McLachlan) levels of approximation.