ROTATION AND INVERSION STATES IN THERMAL E Z ISOMERIZATION OF AROMATIC AZO-COMPOUNDS/

Ab initio calculations in a variation-perturbation scheme have been ca rried out on the three molecules of diazene, phenyldiazene and azobenz ene with a view to clarifying the Z/E isomerization mechanism. It is f ound that, contrary to the usual belief, the rotational isomerization mechanism shows an energy barrier quite comparable to the inversional one and cannot generally be discarded in the Z/E thermal conversion.