Thermal cis, trans geometrical isomerization theoretically involves a 90° twisted, singlet diradical-like transition state which may serve as a base for the examination of structural perturbations. Although thermal rearrangement of hexa-1, trans-3, 5-triene (and all-trans octa-2, 4, 6-triene) to the cis isomer cannot be followed directly owing to subsequent cyclization and 1, 5 hydrogen shifts, activation parameters for disappearance have been ...
