Molecular orbital cross-section of butadiene transformation process

Abstract

The MO energies and coefficients versus the reaction coordinate of the conand dis-rotatory processes in the ring-closure of butadiene are calculated by-using Tang's HMO models. With additional postulates about the molecular geome tries and the atomic orbitals, the contours of the molecular orbitals in both processes at some values of the reaction coordinate are plotted. It is visual toillustrate by means of these drawings the features of the change of the molecular orbitals and the conserved symmetry, giving great help in the concerning teaching. Using these drawings and the corresponding MO data we can easily clarify the divergence on the correlation diagram appearing in literature and expound the role of the noncrossing rule in this field.