I need to predict the geometry of Dichlorine monoxide, using the main link theory: Lewis model, VSEPR and hybridization of molecular orbitals.

First, the Lewis structure is a graphical representation of the pairs of electrons bonding between the atoms of a molecule and the pairs of solitary electrons, which may exist.

Lewis structure

We proceed to predict the geometry of the electron and molecular pair of the chemical species, using the VSEPR model, which is based on the number of electron pairs of the central atom (oxygen) to determine it.

As we have previously stated, the central atom is oxygen. The number of electron pairs of oxygen is four, of these four: two are shared and two are bonding. Therefore, electronic geometry is tetrahedral and molecular gometry is angular:


To conclude, we will explain geometry by hybridization of atomic orbitals. Orbital hybridization is simply the linear combination of the mathematical expressions of the wave functions of the orbitals. We know that there are two types of overlaps:

  • Sigma or frontal bond.
  • Pi or lateral bond.

Here I am asked to study the different overlaps that occur and to explain the consequences on the geometry of that overlap. I suppose there will only be sigma overlap because there are no multiple links. But I can neither say nor explain with certainty what type of overlap and between which electrons or atoms there are and, finally, explain the relevance of this in geometry.

Likewise, ideally the angle should be 120º, but experimentally it is 110.4º. This decrease is due to the presence of two pairs of solitary electrons in the oxygen atom, isn't it? Is there any way to determine such an angle other than in the laboratory, any formula or relationship?

  • $\begingroup$ Welcome to chemistry.se! Are you familiar with molecular orbital theory? You have applied VSEPR theory correctly, but unfortunately within this molecule bonding is not as simple. The two lone pairs at the oxygen will not be equal, similarly to the way they are not equal in water. The best explanation for the different angles is Bent's rule. There will also be pi-backbonding from the chlorine to the oxygen. $\endgroup$ – Martin - マーチン Dec 2 '18 at 18:48
  • $\begingroup$ I understand the theoretical concepts, i.e. I know that a sigma link (occurs in single links) and a pi link (occurs in multiple links). The problem is that I don't know how to apply these concepts to a practical case, like this one. Normally, I am asked for a hybridization scheme (this is to indicate which orbitals overlap, between which electrons the sigma link or pi link is given and to explain how this influences geometry). I've seen several tutorials on the Internet, and none of them get to be very good. I was hoping they could help me here. And finally, what does Bent's rule postulate? $\endgroup$ – aprendiendo-a-programar Dec 2 '18 at 19:16
  • $\begingroup$ Bent's rule is an empirical observation which covers 'fractional' hybridisation. It is very well explained in the question I linked. The fundamental theory that is a basis to the simplifications you are using is molecular orbital theory. It is more involved and harder to learn, but in the end easier to apply. Hybridisation has no effect on the molecular structure, it is a mathematical tool to describe bonding. $\endgroup$ – Martin - マーチン Dec 2 '18 at 19:28
  • $\begingroup$ Tomorrow I start giving the theory of molecular orbitals in theoretical classes. @Martin $\endgroup$ – aprendiendo-a-programar Dec 2 '18 at 19:40

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