Chlorine dioxide isomerization

[caters]

O=Cl=O → O^--Cl-O^- → (cyclic)O-Cl-O

This is an intramolecular reaction which isn't all that common.

The double bonds break, causing the O's to each have a negative charge. This forms an ion. The ion bends and eventually the 2 O's bond with each other forming a ring.

But would this really happen? I mean yes, sunlight is enough to split Cl₂ into 2 Cl radicals but would it be enough to break the O-Cl double bond so that the ion can form?

 

[DrDu]

To begin with: Why should two negative ions form a bond? They repel each other and also have no unpaired electrons for bonding.
The second point: ClO2 is already bent. Probably there are also bonding resonance valence structures contributing to the energetic stabilization of the molecule. Note that this is not an isomerisation.

 

[caters]

The oxygens can use their lone pairs to form bonds just like they do when bonding with other molecules. And yes I know that there is a form that has a triple bond and a single bond that is a resonance structure. But the cyclic peroxide is not a resonance structure, it is an isomer.

 

[DrDu]

But where should the lone pairs go to, if both oxygens already have a filled octet?
Also, I was not referring to a resonance structure with a triple and a single bond but in the peroxidic resonance structure.
While this resonance structure makes but a small contribution to the bonding in the electronic ground state, one may wonder whether there exists an excited electronic state which is mainly peroxidic.