Unrestricted hartree-fock calculation of spin distributions in some radical anions exhibiting restricted rotation about a carbon carbon bond

Abstract

In the radical anions of trans-stilbene, trans-1,2-bis(4-pyridyl)-ethylene, cis and transterephthalaldehyde and benzaldehyde it has been found earlier by ESR experiments that the two ortho protons, as well as the two meta protons of the six-membered ring are not equivalent. We have made a systematic study of spin distributions in these systems by employing the UHF (Unrestricted Hartree Fock) and UHFAA (UHF incorporating the annihilation of the quartet spin component) methods. Satisfactory agreement with the experimental results has been obtained within the framework of these theories and without invoking the so called "α effect" or "β effect".