I searched the net and a lot of books, but I was unable to find any information about dichlorine pentoxide.

  1. Does dichlorine pentoxide($\ce{Cl2O5}$) exist?
  2. If it doesn't exist, then why so?
  3. If dibromine pentoxide and iodine pentoxide do exit, then why not dichlorine pentoxide?
  • 1
    $\begingroup$ I've never heard of this site, but here it is with a couple example reactions for what it's worth ;) $\endgroup$
    – airhuff
    Commented Feb 10, 2017 at 6:38
  • $\begingroup$ Here, it says it is unknown at present. $\endgroup$ Commented Feb 10, 2017 at 11:41
  • $\begingroup$ That is a pretty old book though (Published in 2001). $\endgroup$
    – Prakhar
    Commented Feb 10, 2017 at 14:26
  • 2
    $\begingroup$ Ok , for once lets agree that Dichlorine Pentoxide doesnt exist. Then why is that so? Dibromine pentoxide(en.wikipedia.org/wiki/Dibromine_pentoxide) and Iodine Pentoxide does exit, then why not Dichlorine Pentoxide? $\endgroup$
    – Prakhar
    Commented Feb 10, 2017 at 17:34
  • 1
    $\begingroup$ I've seen this reaction given in half a dozen websites I've never heard of before: $\ce{Cl2O5 + H2O -> 2HClO3}$. The only one with any discussion is in Russian and I'm trying to find someone who can read that. It's just a couple sentences though. I've also seen it mentioned in nomenclature lessons, i.e. "$\ce{Cl2O5}$ chlorine dioxide from chloric oxide (V)" . Still nothing solid about it though. $\endgroup$
    – airhuff
    Commented Mar 1, 2017 at 15:48

1 Answer 1


The crux of this (Russian) article is that $\ce{Cl2O5}$ is not stable enough to be isolated in a pure form, and if it were, it would be strongly acidic oxidizer.

This web site is representative of several others that simply give example reactions of the compound (the second reaction being the most common exampe):

$$\ce{NiCl2 + 3O2 -> NiO + Cl2O5}$$ $$\ce{H2O + Cl2O5 -> 2HClO3}$$

The statement in the first article and the simple fact that there is such a dearth of information about this compound suggest that it really only exists as a transient, unstable, oxidizing acid that apparently has not been isolated as a stable compound. Furthermore, information can be found in Wikipedia and/or PubChem for $\ce{Cl2O_x}$, where $x \in 1, 2, 3, 4, 6, 7$.


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