Platonic hydrocarbon
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2008-07-01T14:18:52Z
LarrisM
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linked truncated icosahedron
'''Platonic hydrocarbons''' are the [[molecule|molecular]] representation of [[platonic solid]] geometries with vertices replaced by [[carbon]] [[atom]]s and with edges replaced by [[chemical bond]]s. Not all platonic solids have a molecular counterpart:
* [[Tetravalent]] carbon excludes an [[icosahedron]] (5 edges meeting at each vertex) as a feasible objective;
* [[Angle strain]] prohibits an [[octahedron]]. Since 4 edges meet at each corner, there would be no hydrogen atoms, and this hypothetical octahedron molecule would be an [[allotrope]] C<sub>6</sub> of elemental carbon, not a hydrocarbon.
The following platonic hydrocarbons, on the other hand, have been [[chemical synthesis|synthesised]]:
* [[Tetrahedrane]] (C<sub>4</sub>H<sub>4</sub>) but only with proper substituents;
* [[Cubane]] (C<sub>8</sub>H<sub>8</sub>);
* [[Dodecahedrane]] (C<sub>20</sub>H<sub>20</sub>).
Note that with increasing number of carbon atoms in the frame, the geometry will eventually approximate a sphere. This is ultimately accomplished in [[fullerene]] although not a Platonic hydrocarbon itself (Buckminsterfullerene, C<sub>60</sub>, has the shape of a [[truncated icosahedron]], an [[Archimedean solid]]).
<gallery>
Image:Tetrahedrane-3D-balls.png |Tetrahedrane
Image:Cubane-3D-balls.png |Cubane
Image:Dodecahedrane-3D-balls.png |Dodecahedrane
</gallery>
== References ==
* Henning Hopf, ''Classics in Hydrocarbon Chemistry'', Wiley VCH, 2000.
{{commonscat|platonic hydrocarbons}}
[[Category:Hydrocarbons]]
[[Category:Platonic solids|Hydrocarbons]]