Platonic hydrocarbon 1620703 222865696 2008-07-01T14:18:52Z LarrisM 4710198 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]]