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Why doesn't carbon form bonds with itself to form a molecule? Carbon shows the property of catenation, so why doesn't it form a cyclic molecule such as:

 C = C 
 ‖   ‖ 
 C = C
Buck Thorn
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Harsh Wasnik
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    graphene, diamond, fullerenes ... – gilleain Nov 15 '18 at 09:23
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    also relevant : https://chemistry.stackexchange.com/questions/43887/how-small-is-the-smallest-known-carbon-ring-containing-only-double-bonds – gilleain Nov 15 '18 at 11:58
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    buckyball also... – MaxW Nov 15 '18 at 20:55
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    Diamond and graphene if not engineered down do not qualify as molecules. Buckyballs is a nik for Buckminsterfullerenes. See Oscar Lanzi below for an answer – Alchimista Nov 17 '18 at 17:43
  • That specific molecule would be monstrously unstable due to ring strain. But plenty of other molecules with just carbon would not be and many exist. – matt_black Dec 18 '23 at 12:38

1 Answers1

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They do form. Besides fullerenes, there are carbon molecules with varying numbers of atoms around some stars[1]. Vaporized graphite in such envirinments produce chains of 3 to 30 carbobs and larger spheroidal clusters of 40 to as many as 100 carbins. These may combine with hydrogen and nitrogen to form circumstellar polyynes. Such molecular forms are, of course, less stable than the macromolecular structures we more commonly see under ambient conditions.

Reference

  1. H. W. Kroto, J. R. Heatth, S. C. O'Brien, R. F. Curl. R. E. Smalley (1987). "Long Carbon Chain Molecules in Circumstellar Shells". The Astrophysical Journal 314, 352-355.
Oscar Lanzi
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