title: The delocalization index as an electronic aromaticity criterion: application to a series of planar polycyclic aromatic hydrocarbons.
abstract: This work introduces a new local aromaticity measure, defined as the mean of Bader's electron delocalization index (DI) of para-related carbon atoms in six-membered rings. This new electronic criterion of aromaticity is based on the fact that aromaticity is related to the cyclic delocalized distribution of pi-electrons. We have found that this DI and the harmonic oscillator model of aromaticity (HOMA) index are strongly correlated for a series of six-membered rings in eleven planar polycyclic aromatic hydrocarbons. The correlation between the DI and the nucleus-independent chemical shift (NICS) values is less remarkable, although in general six-membered rings with larger DI values also have more negative NICS indices. We have shown that this index can also be applied, with some modifications, to study of the aromaticity in five-membered rings.
authors.affiliation: Institut de Química Computacional, Departament de Química Universitat de Girona 17071 Girona, Catalonia, Spain.
authors.forename: Jordi
authors.initials: J
authors.lastname: Poater
authors.forename: Xavier
authors.initials: X
authors.lastname: Fradera
authors.forename: Miquel
authors.initials: M
authors.lastname: Duran
authors.forename: Miquel
authors.initials: M
authors.lastname: Solà