Collect. Czech. Chem. Commun. 2009, 74, 147-166
Published online 2009-01-29 18:12:29

The close relation between cyclic delocalization, energy effects of cycles and aromaticity

Robert Poneca,*, Stijn Fiasb, Sofie Van Dammeb, Patrick Bultinckb, Ivan Gutmanc and Sonja Stankovićc

a Institute of Chemical Process Fundamentals, Academy of Sciences of the Czech Republic, v.v.i., 165 02 Prague 6-Suchdol, Czech Republic
b Department of Inorganic and Physical Chemistry, Ghent University, Krijgslaan 281, B-9000 Ghent, Belgium
c Faculty of Science, University of Kragujevac, P.O. Box 60, 34000 Kragujevac, Serbia


New evidence questioning the multidimensionality of the aromaticity phenomenon exemplified in what is called orthogonality between the classical (structural and energetic) and magnetic aromaticity indices and measures is reported. For this purpose, the recently proposed methodologies for the quantitative characterization of the energy benefits associated with the cyclic arrangement of mobile π-electrons in polycyclic aromatic hydrocarbons are compared with the indices characterizing the extent of cyclic delocalization in the corresponding conjugated circuits. The reported close correlation between both types of indices implies that no discrepancies between classical and magnetic aromaticity measures exist provided the comparison is based on the indices of inherently local nature and/or the interfering contributions of contaminating conjugated circuits is properly taken into account in the description of aromaticity measures like topological resonance energy (TRE) or nucleus independent chemical shift (NICS).

Keywords: Aromaticity; Arenes; Electron delocalization; Topological resonance energy; Polycyclic aromatic hydrocarbons; Chemical theory.

References: 58 live references.