Quadruple bond between two carbon atoms

In summary, the possibility of a quadruple bond between two carbon atoms is still being debated in the scientific community. The wikipedia article on dicarbon and valence bond theory suggest a double bond is more likely due to the number of unpaired electrons in carbon atoms. However, in electronically excited states, higher bond orders may be present. The concept of bond order is based on approximative models and may not accurately reflect bond lengths and strengths. Ultimately, determining the bond order between two carbon atoms is a contentious topic among theorists.
  • #1
pierce15
315
2
I was wondering if a quadruple bond between two carbon atoms would be possible. I found this on wikipedia about "dicarbon": http://en.wikipedia.org/wiki/Diatomic_carbon, which is related to this question, since what I'm describing is an isomer of dicarbon. Anyone have any ideas?
 
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  • #2
The wikipedia article is not very good. Valence bond theory also predicts a double bond as carbon atoms have two unpaired electrons. It is not a requirement of VB theory for the molecule to obey the octet rule.
Higher bond orders may be present in electronically excited state of C2.
 
  • #3
So what do you think about a quadruple bond?
 
  • #4
Whether bonding in dicarbon is better described as a double or quadruple bond is still being debated, see http://www.ch.imperial.ac.uk/rzepa/blog/?p=10733 .

Assigning definite integer-valued bond orders to chemical bonds is just a property of the approximative model used to describe bonding.
 
  • #5
Whatever else one may or may not say about C2, if it is described with a single closed-shell determinant wave function (i.e., with Hartree-Fock or Kohn-Sham), one can rotate its occupied orbitals into two equivalent doubly-occupied non-standard sigma bond orbitals and two standard doubly occupied pi bond orbitals via orbital localization (Pipek-Mezey-like).

As the theoretical basis for bond order concept is closely related to this form of MO theory (which, for C2, is not entirely beyond question--it has low lying excited states), one could formally interpret this as a quadruple bond. Or as a double bond or triple bond, depending on how one wishes to interpret the non-standard sigma system.

In short, it is the perfect fighting ground for bored theorists 8).
 
  • #6
Another question is what a number like "bond order" really tells you.
What we observe are bond lengths and strengths and not bond orders.
 

1. What is a quadruple bond between two carbon atoms?

A quadruple bond between two carbon atoms is a type of chemical bond where four pairs of electrons are shared between the two carbon atoms. This results in a very strong bond that is difficult to break.

2. How is a quadruple bond formed between two carbon atoms?

A quadruple bond between two carbon atoms is formed when four atomic orbitals from each carbon atom overlap. These orbitals contain a total of eight electrons, which are shared between the two carbon atoms to form the quadruple bond.

3. What is the difference between a double bond and a quadruple bond?

The main difference between a double bond and a quadruple bond is the number of shared electron pairs. A double bond consists of two pairs of shared electrons, while a quadruple bond consists of four pairs of shared electrons. This makes the quadruple bond stronger and shorter in length compared to a double bond.

4. What are some examples of molecules with a quadruple bond between two carbon atoms?

Some examples of molecules with a quadruple bond between two carbon atoms include carbon monoxide (CO), dinitrogen (N2), and cyanogen (C2N2). These molecules are all very stable and have unique properties due to the presence of the quadruple bond.

5. Can a quadruple bond form between atoms other than carbon?

Yes, a quadruple bond can form between atoms other than carbon. In addition to carbon, elements such as nitrogen, oxygen, and phosphorus have been found to form quadruple bonds with each other. However, these bonds are much less common than double or single bonds.

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