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QTAIM n ‐center delocalization indices as descriptors of aromaticity in mono and poly heterocycles
Author(s) -
Mandado Marcos,
GonzálezMoa María J.,
Mosquera Ricardo A.
Publication year - 2006
Publication title -
journal of computational chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.907
H-Index - 188
eISSN - 1096-987X
pISSN - 0192-8651
DOI - 10.1002/jcc.20468
Subject(s) - aromaticity , antiaromaticity , delocalized electron , chemistry , electron delocalization , computational chemistry , molecule , resonance (particle physics) , electron , physics , atomic physics , organic chemistry , quantum mechanics
The implementation of the n ‐center electron delocalization indices, n ‐DIs, and n ‐order electron localization indices, n ‐LIs, within the framework of the quantum theory of atoms in molecules, QTAIM, is performed. n ‐DIs are shown to be very useful to study the local aromaticity in monocyclic and polycyclic compounds. Total and π n ‐DIs from n = 4 to 7 were computed for a series of typical 4, 5, 6, and 7‐center aromatic and antiaromatic rings. For n ≥ 5 the π n ‐DI accounts for the 95% of the total n ‐DI and can be employed alone to measure the aromaticity. A scaling factor on the n ‐DIs is required in order to compare the aromaticity of [5c‐6e] and [6c‐6e] rings, the same correction allows to estimate the relative aromatic stabilization of polycyclic compounds using the sum of its values for individual rings. This is called Effective Scaled Electron Delocalization, ESED. The comparison with other aromaticity indices reflects a good correlation between ESED and both resonance energies, and HOMA indices. The most important differences between scaled π n ‐DIs and NICS(0) indices are found for compounds that contain rings with different number of centers or π electrons. © 2006 Wiley Periodicals, Inc. J Comput Chem, 2007