Take the 2-minute tour ×
Chemistry Stack Exchange is a question and answer site for scientists, academics, teachers and students. It's 100% free, no registration required.

I've heard that, even though according to Molecular Orbital Theory there is no chance of having nobel gases bonded to each other, it is not totally impossible. For example, under extreme conditions, Ar2 can be synthesised.

So I am wondering whether a carbon can make 5 bonds if the required conditions are provided.

share|improve this question
add comment

5 Answers

up vote 5 down vote accepted

Carbon cannot have more then 4 double-electron bonds in reasonable conditions. However, in can form a bond with 5 or 6 atoms, like $Fe_6C$ fragment, where iron atoms form octahedron around the carbon atom. However, the sum of orders of 6 C-Fe bonds will be still 4.

The situation is different if we consider exited states. Indeed, it is possible for hight excited state of carbon to be able to form 5 or 6 bonds. The resulting structure, however, will die quickly.

Noble gases are able to form molecules in excited states, or, to be precise, their molecules are stable only in excited state. This kind of molecules is known as excimer (excited dimer).

share|improve this answer
add comment

Carbon can make 5 bonds on methanium ($CH_5^+$). It is a kind of carbonium ion and superacid. Methanium can be produced in the laboratory as a dilute and low-temperature gas.

Reaction:
$CH_4 + H^+ → CH_5^+$

share|improve this answer
add comment

There are stable crystal structures where one could notionally see carbon atoms with more than 4 'bonds'. One example that comes to mind is a carborane unit; e.g. see

http://en.wikipedia.org/wiki/Carborane

For example. But of course, such 'bonds' are a notional thing really and don't reflect the true nature of the underlying electronic structure.

share|improve this answer
    
Your comment on notional bonds can be said of any bond unless you use a theory such as Natural Bond Order analysis, which does not necessarily contradict the penta-bonded carborane. –  Deathbreath Jan 29 '13 at 19:40
add comment

The hypervalent carbon do exist. Look at this 2005 J. of Am. Chem. Soc. article:

http://pubs.acs.org/doi/abs/10.1021/ja043802t enter image description here

X-ray structure confirmed the 10-C-5 structure.

share|improve this answer
add comment

Here it is a nice example with TMS of a carbon covalently bound to 5 other atoms:

http://onlinelibrary.wiley.com/doi/10.1002/anie.200601164/abstract

share|improve this answer
    
Welcome to Chemistry.SE. Would you be willing to summarize the article you linked? For many of our users it is likely behind a paywall. –  Ben Norris Oct 3 '13 at 11:21
add comment

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.