Tetradehydroadamantane-1,3,5,7-di- and tetracations and their helium and hydride inclusion complexes: Spherical aromaticity and evidence for a bonding interaction between carbon and helium

Bucher, G. , Kohler, F. and Herges, R. (2008) Tetradehydroadamantane-1,3,5,7-di- and tetracations and their helium and hydride inclusion complexes: Spherical aromaticity and evidence for a bonding interaction between carbon and helium. Journal of Physical Chemistry A, 112(40), pp. 9906-9910. (doi: 10.1021/jp803594w)

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Abstract

The unusual stability of the experimentally known 1,3-dehydro-5,7-adamantyl dication was previously explained by four-center two-electron aromaticity with three-dimensional (tetrahedral) topology. Magnetic criteria (ACID and ring-current analysis) now demonstrate that there is also a very strong contribution from hyperconjugation with all six methylene bridges. The delocalized system of electrons thus includes all valence electrons, and the structure, therefore, should rather be described as a spherically aromatic 50-electron system. The corresponding T-d-symmetric tetracation with 48 electrons is antiaromatic and not a minimum structure. With a He atom or a hydride ion at the center of the cage, the tetracation is predicted to form a kinetically stable complex. Magnetic criteria demonstrate that the antiaromaticity is greatly reduced, and a bond analysis hints at bonding interactions between He (and H-) and the carbon atoms of the adamantane cage.

Item Type:Articles
Keywords:2(N+1)(2) rule, acid, aromaticity, atoms, bond, cage, carbon, complex, complexes, delocalization, electron, fullerenes, ion, stability, structure, system, valence
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Bucher, Dr Goetz
Authors: Bucher, G., Kohler, F., and Herges, R.
College/School:College of Science and Engineering > School of Chemistry
Journal Name:Journal of Physical Chemistry A
Publisher:American Chemical Society
ISSN:1089-5639
ISSN (Online):1520-5215
Published Online:11 September 2008

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