The total pi-electron delocalization of a series of classical aromatic and antiaromatic organic compounds is separated into ortho (1,2), meta (1,3), para (1,4), and successive contributions (the so-called delocalization crossed terms) and the changes that take place in these crossed terms when two electrons are added or removed are analyzed. Our results show that these changes follow a similar alternation pattern in all cases. The patterns found represent a kind of electronic footprints that makes it possible to discern between aromatic and antiaromatic systems.
[Show abstract][Hide abstract] ABSTRACT: A series of monocyclic planar inorganic compounds with single, double, and triple (anti)aromatic character has been studied.
The electron delocalization and aromaticity of these compounds have been assessed by means of two-center and multicenter electronic
delocalization indices and their σ-, π-, and δ-components. Results show that these indices are excellent predictors of the
σ-, π-, and δ-aromatic character of all-metal and semimetal clusters.
KeywordsElectronic multicenter delocalization indices–Inorganic rings–Aromaticity–DFT calculations
[Show abstract][Hide abstract] ABSTRACT: In this paper we give a new definition of the softness kernel based on the exchange-correlation density. This new kernel is shown to correspond to the change of electron fluctuation upon external perturbation, thus helping to bridge the gap between conceptual density functional theory and some tools describing electron localization in molecules. With the aid of a few computational calculations on diatomics we illustrate the performance of this new computational tool.
The Journal of Physical Chemistry A 05/2011; 115(45):12459-62. DOI:10.1021/jp200731d · 2.69 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The absorption spectra and excited state dipole moments of four differently substituted fulvenes have been investigated both experimentally and computationally. The results reveal that the excited state dipole moment of fulvenes reverses in the first excited singlet state when compared to the ground state. The oppositely polarized electron density distributions, which dominate the ground state and the first excited singlet state of fulvenes, respectively, reflect the reversed π-electron counting rules for aromaticity in the two states (4n + 2 vs. 4n, respectively). The results show that substituents indeed influence the polarity of fulvenes in the two states, however, cooperative interactions between the substituents and the fulvene moiety are most pronounced in the ground state.
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