Document Detail


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.
MedLine Citation:
PMID:  18785696     Owner:  NLM     Status:  PubMed-not-MEDLINE    
Abstract/OtherAbstract:
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 Td-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.
Authors:
Götz Bucher; Felix Köhler; Rainer Herges
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Publication Detail:
Type:  Journal Article     Date:  2008-09-11
Journal Detail:
Title:  The journal of physical chemistry. A     Volume:  112     ISSN:  1520-5215     ISO Abbreviation:  J Phys Chem A     Publication Date:  2008 Oct 
Date Detail:
Created Date:  2008-10-03     Completed Date:  2008-12-03     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9890903     Medline TA:  J Phys Chem A     Country:  United States    
Other Details:
Languages:  eng     Pagination:  9906-10     Citation Subset:  -    
Affiliation:
Lehrstuhl fur Organische Chemie II, Ruhr-Universitat Bochum, Universitatsstrasse 150, 44801 Bochum, Germany. goebu@chem.gla.ac.uk
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