Theoretical studies of the decyclization /cyclization of the C6H5 radical

The decyclization/cyclization reactions of the phenyl radical have been investigated by means of ab initio theory. The geometries and structures of the phenyl radical, the open-chain radical and also the transition state were optimized at the UHF/6-31G∗ level, and their relative energies refined by the spin-projected (UMP3(PUMP3) method with UHF/6-31G∗ zero-point energy corrections. Evaluations of the unimolecular rate constant for both directions of this isomerization reaction were carried out in terms of Rice-Ramsperger-Kassel-Marcus theory.