SIGMA-PI ENERGY DIAGRAMS FOR SUBSTITUTED RINGS

The recently developed sigma-pi energy separation technique was applie d to substituted monocyclic ring systems. Modified correlation diagram s are presented which allow the influence of the substituent on the si gma and pi energies to be assessed. The slopes of the sigma and pi ele ctron energy curves can be used to classify aromatic, non-aromatic and anti-aromatic compounds. A two-dimensional resonance coordinate repre sentation shows a clustering of compounds of the three classes in dist inctly different regions of this plane.