Localisation and reversal of paratropic ring currents in molecules with formal anti-aromatic electron counts
UNSPECIFIED (2004) Localisation and reversal of paratropic ring currents in molecules with formal anti-aromatic electron counts. In: ESF Exploratory Workshop on New Perspectives on Aromaticity, EXETER, ENGLAND, JUL 05-09, 2003. Published in: PHYSICAL CHEMISTRY CHEMICAL PHYSICS, 6 (2). pp. 289-294.Full text not available from this repository.
Official URL: http://dx.doi.org/10.1039/b311255a
The aromatic character of the six smallest members of the of alpha,omega-bicyclopentadiene-polyacene series (1(n)) has been assessed using magnetic and energetic criteria. Current density maps (CTOCD-DZ/6-31G**//B3LYP/6-31G**) show that. along the series, the ring current changes from paratropic in pentalene (1(0)) and s-indacene (1(1)), through quenched in 1(2) and 1(3), to diatropic in 1(4) and 1(5). These changes are rationalised in terms of orbital contributions to current. Valence bond calculations (VB/6-31G//B3LYP/6-31G**) in which the pi system is composed of strictly atomic p-orbitals, show that the electronic structures in these homologous series can be described in terms of the two closed-shell Kekule resonance structures for the smallest molecules, but that in the larger molecules allyl-polyacene-allyl biradical structures prevail, owing to the larger resonance energies. This trend in electronic structure parallels the switch from paratropic to diatropic character.
|Item Type:||Conference Item (UNSPECIFIED)|
|Subjects:||Q Science > QD Chemistry
Q Science > QC Physics
|Journal or Publication Title:||PHYSICAL CHEMISTRY CHEMICAL PHYSICS|
|Publisher:||ROYAL SOC CHEMISTRY|
|Official Date:||21 January 2004|
|Number of Pages:||6|
|Page Range:||pp. 289-294|
|Title of Event:||ESF Exploratory Workshop on New Perspectives on Aromaticity|
|Location of Event:||EXETER, ENGLAND|
|Date(s) of Event:||JUL 05-09, 2003|
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