Accurate calculations of the structure and energy of the π- and σ-succinimidyl radicals: an ab initio study including electron correlation

Abstract

Ab initio calculations of the structure and energies of the π and σ states of the succinimidyl radical have been carried out including electron correlation. The results are found to be extremely sensitive both to basis set size and to the degree of electron correlation included. With molecular geometries obtained using a multiconfiguration SCF wavefunction where appropriate, a 6-31G* basis and large scale Cl calculations resulted in the following relative energies (in kJ mol^–1); S_π, 0.0; S_σ(N), 21.5; S_σ(O), 168.9.