Electronic structure of α-substituted vinyl radicals

Some α-substituted vinyl radicals are produced by γ-irradiation of α-chloro vinyl and acetylenic compounds adsorbed on molecular sieves. The electronic structure of CH2=Ċ-C6H5 and CH2=Ċ-COOH is discussed on the basis of the observed E.S.R. spectra and the energies and spin-density distributions given by INDO calculations. In both cases, minimum energy is obtained for a linear π radical when the CH2 plane is perpendicular to the plane of the substituent C6H5 or COOH. The fit between calculated and experimental hyperfine constants is reasonably good (10 per cent).