Icosahedral molecules

The nature of the electronic states for fullerene molecules depends sensitively on the number of 7r-electrons in the fullerene. The number of 7r-electrons on the Cgo molecule is 60 (i.e., one w electron per carbon atom), which is exactly the correct number to fully occupy the highest occupied molecular orbital (HOMO) level with hu icosahedral symmetry. In relating the levels of an icosahedral molecule to those of a free electron on a thin spherical shell (full rotational symmetry), 50 electrons fully occupy the angular momentum states of the shell through l = 4, and the remaining 10 electrons are available... 

Stecher, T. P. 1969 Interstellar extinction in the ultraviolet. Astrophys. J. 157, L125-L126. Weeks, D. E. Harter, W. G. 1989 Rotation-vibration spectra of icosahedral molecules. Icosahedral symmetry, vibrational eigenfrequencies, and normal modes of buckminsterfullerene. J. chem. Phys. 90, 4744. 

In this paper, we have introduced the polyhedral representation of reaction surfaces for chemical interconversion processes, and applied it to the interconversion of JT distortions of icosahedral molecules. In this case, the minimal hypersurface is 5D. Two types of distortions are investigated pentagonal and trigonal. Interconversions between pentagonal distortions can simply be represented by a triangulation of the projective plane. This is the prototype of a JT surface in a... 

With respect to immobile chiroids, the appropriate symmetries are given by the familiar finite point groups C, (nonaxial), C (monoaxial), Dn (dihedral), T (tetrahedral), 0 (octahedral), and I (icosahedral). Molecules that belong to the first three groups are commonplace molecules with ground-state symmetries T [example tetrakis(trimethylsilyl)silane],39 O (example appoferritin 24-mer),40 and 1 (example human rhinovirus 60-mer),40 are relatively uncommon. 

In carbon smoke samples prepared from vaporized graphite at elevated quenching gas pressures (e.g.> 100 Torr He) new absorption features have been observed in the infrared (the strongest at 1429, 1183, 577, and 528 cm ). Broader features also have been observed in the ultraviolet (the strongest at 340, 270, and 220 nm). By studying C-enriched samples we have shown that the infrared absorptions are produced by large, pure carbon molecules. The evidence supports the idea that the features are produced by the icosahedral molecule. 

BioH8(CO)2]. ) The closely related stable, volatile, icosahedral molecule [closo-1,12-Bi2Hio(CO)2] can be prepared by the reaction of H2B12H12.4H2O with CO at 130°C and 800-1000 atm. pressure in the presence of dicobaltoctacarbonyl as catalyst. In the absence of this catalyst, approximately equal amounts of the 1,7- and 1,12-isomers are formed. 

Fig. 2e). This is despite solution-binding constants favoring C70 compiexation of C60, and thus crystalpacking forces are important. The same 1 1 complex also forms in the presence of Cg4 and 1.2-dicarborane (1,2-C2B10H12). an icosahedral molecule that is independently drawn into the cavity of the calixarene. ... 

Icosahedral symmetry is less obvious and thus more intriguing than cubic symmetry. Whilst tetrahedral and octahedral molecules were already known before the turn of the nineteenth/twentieth century, the first structural study of an icosahedral molecule was the closo-dodecaborane, in 1960. More examples would... 

Fowler, P.W., Ceulemans, A. Symmetry relations in the property surfaces of icosahedral molecules. Mol. Phys. 54, 767 (1985)... 

Interestingly similar drawings may be encountered in the study of rotational energy surfoces of cubic and icosahedral molecules. See Harter WG (1984) Journal of Statistical Physics 36 749 Harter WG, Weeks DE (1986) Chem. Phys. Lett. 132 387 O Brien MCM (1969) Phys. Rev. 187 407... 

When working with an icosahedral molecule such as or C o life is much easier if... 

In Fig. 4.28, the IR spectrum of buckminsterfullerene which shows only four strong bands is reproduced. They are indeed the bands expected for the free, truncated icosahedral molecule depicted in Fig. 4.20. 

Haymet AD (1986). Footballene a theoretical prediction for the stable, truncated icosahedral molecule Cjj. JAm Chem Soc. 108 319-321. 

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