Aromaticity in terms of ring critical point properties

The properties derived from topological analysis of electron density at the ring critical point, RCP, have been used to model six different aromaticity indices. The intercorrelations between various aromaticity indices and eight properties extracted from the RCPs of 43 aromatic rings have been investigated. It was found that individual RCP properties cannot be considered as reliable quantitative characteristics of π-electron delocalization in heterocyclic compounds. We showed that it is possible to describe aromaticity indices in terms of principal components derived from density based properties estimated at RCP of aromatic rings. The resulted models yield correlation coefficients greater than 0.9 for five of total six aromaticity indices studied here.