Talk:Carbyne

Hund's rule

This article claims that carbynes violate Hund's rule. If you look up the article on Hund's Rule you will see that only one violation ("the first" observed, according to the article) has been experimentally confirmed and that this was in 2004. The exception is the molecule 5-Dehydro-m-xylylene, but this particular molecule's carbon atoms all are in R-C-R' configurations; it does not appear that a carbyne is present in 5-Dehydro-m-xylylene.

Do carbynes violate Hund's rule, or was this claim made mistakenly? I added a dubious tag after skimming the existing citations; if this is a verifiable claim, then this article AND the article on Hund's rule(s) needs to be updated. I hope this tag and my edit here help to clarify the article and the discussion of Hund's rule and carbynes! Thanks! Spiral5800 (talk) 10:43, 7 January 2013 (UTC)

Hund formulated his rule for atoms with several orbitals of equal energy. It should only be applied to molecules when the orbitals considered are of equal energy. The cited article by Ruzsicska et al. does not mention Hund's rule. It gives the electronic configuration of CH as 1σ² 2σ² 3σ² 1π. The molecule is a doublet and not a quartet simply because the 3σ orbital is lower than the 1π. It is not an exception to Hund's rule because the rule does not apply when the orbitals are not degenerate. CF, CCl and CBr are analogous. The mention of Hund's rule should be deleted from this article and the electron configuration explained properly.

The xylylene derivative is different because there are three localized orbitals which are separated in space and of almost equal energy, so that there are in fact three unpaired electrons as suggested by Hund's rule, but two of them have spin up and one has spin down. In that sense it is an exception. This also needs to be explained properly, either in the Hund's rule article or in the article on the molecule in question. Dirac66 (talk) 02:45, 26 January 2013 (UTC)

I am removing the "Expert attention needed" tag since the dispute appears to have been resolved. --Jorge Stolfi (talk) 23:39, 27 January 2013 (UTC)

Why does "ethylidyne" redirect here?

Not mentioned in article. 86.130.41.222 (talk) 13:47, 16 September 2014 (UTC)

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