Investigation of a putative Mobius aromatic hydrocarbon. The effect of benzannelation on Mobius [4n]annulene aromaticity

Journal article


Publication Details

Author(s): Castro C, Chen Z, Wannere C, Jiao H, Karney W, Mauksch M, Puchta R, van Eikema Hommes N, Schleyer P
Journal: Journal of the American Chemical Society
Publisher: American Chemical Society
Publication year: 2005
Volume: 127
Journal issue: 8
Pages range: 2425-2432
ISSN: 0002-7863


Abstract


The first experimental example of a [4n]annulene derivative with one Mobius twist, 1, was synthesized recently [Ajami, D.; Oeckler, O.; Simon, A.; Herges, R. Nature 2003, 426, 819] and was purported to possess aromatic character. However, critical analysis of the published crystallographic data indicates that the Mobius [16]annulene core of 1 shows large bond alternation (Deltar up to 0.157 Angstrom). Delocalization in this core is inhibited by large dihedral angles, which hinders effective pi overlap. This conclusion is supported by computational results (B3LYP/6-311+G(**)) on 1 and several less benzannelated derivatives, based on geometric (Deltar, Deltar(m), Julg A, HOMA) and magnetic (NICS, magnetic susceptibility exaltation) criteria of aromaticity. That benzannelation results in bond localization in the [16]annulene core is shown by additional computations on benzannelated derivatives of other Mobius aromatic species. Additionally, the aromatic stabilization energy (ASE) of 1 has been reinvestigated using two different procedures. Evaluation of uncorrected ISEII values of just the polyene bridge portion of 1 and its Huckel counterpart suggests that stabilization of 1 relative to its Huckel isomer is confined to the polyene bridge and is not due to a delocalized pi circuit. Furthermore, application of s-cis/s-trans corrections lowers the ISEII value of 1 from 4.0 kcal/mol to 0.6 kcal/mol, suggesting that 1 is nonaromatic.



FAU Authors / FAU Editors

Puchta, Ralph PD Dr.
Naturwissenschaftliche Fakultät
Schleyer, Paul Prof. Dr.
Naturwissenschaftliche Fakultät
van Eikema Hommes, Nico Dr.
Computer-Chemie-Centrum


How to cite

APA:
Castro, C., Chen, Z., Wannere, C., Jiao, H., Karney, W., Mauksch, M.,... Schleyer, P. (2005). Investigation of a putative Mobius aromatic hydrocarbon. The effect of benzannelation on Mobius [4n]annulene aromaticity. Journal of the American Chemical Society, 127(8), 2425-2432. https://dx.doi.org/10.1021/ja0458165

MLA:
Castro, Claire, et al. "Investigation of a putative Mobius aromatic hydrocarbon. The effect of benzannelation on Mobius [4n]annulene aromaticity." Journal of the American Chemical Society 127.8 (2005): 2425-2432.

BibTeX: 

Last updated on 2018-29-06 at 09:23