CONROTATORY AND DISROTATORY PATHWAYS IN THE ELECTROCYCLIC ISOMERIZATION OF CYCLOBUTENE TO CIS-BUTADIENE - THE SPIN-COUPLED VIEWPOINT

摘要

Spin-coupled theory is used to study the changes which occur in the electronic wave function as a system moves along the intrinsic reaction coordinate (IRC) for the case of conrotatory and disrotatory motion in the ground-state electrocyclic interconversion of cyclobutene to cis-butadiene. It is shown that the reaction is already well under way in the conrotatory case at the transition point (considerable cis-butadiene character), but the system still retains an overwhelming reactant (cyclobutene) character for the disrotatory motion. In both the conrotatory and disrotatory cases, the sharp changes in the weights of the two spin couplings, associated with the onset of bond breaking or bond formation, are shown to occur at points along the IRC well after the transition point. (C) 1997 American Institute of Physics. [References: 38]