How many equal Xe–O bond length are present in (XeO_6)-3?

Question

I tried to solve this problem by drawing a structure but the structure did not give me any answer and I was not able to draw the proper structure please help me out.

what level of theory are you looking at? VSEPR? MO? I don't want to delve into anything MO (those stuffs that abuses hydrogen atom solution. meh. not a believer.). With VSEPR, if you show what you have done so far, I can take a look. — Argyll, Sep 05 '18 at 03:34
@Argyll are you serious about MO theory? You don’t have to believe in it, but that would put you at odds with the majority of chemical literature published in the last few decades. If you’re joking, it’s hard to tell. — orthocresol, Sep 05 '18 at 04:57
On topic, I have some suspicion that this odd-electron ion does not actually exist. $\ce{XeO6^4-}$ does, though. — orthocresol, Sep 05 '18 at 04:58
Protonation of perxenate ion yields $\ce{(HXeO6)^3-}$. See: https://en.m.wikipedia.org/wiki/Perxenate — Nilay Ghosh, Sep 05 '18 at 08:36
!. Ions aren't compounds 2. Such ion/radical is most probably only transient intermediate in redox reactions. 3. If it's some task then you probably misunderstood or there was misprint. — Mithoron, Sep 05 '18 at 16:40
@orthocresol: majority of chemical literature????? you are overblowing what makes up MO theory here. — Argyll, Sep 06 '18 at 11:53
As for $\ce{[XeO6]^{3-}}$, it's not unlikely that the question asks for an answer based on MO even if the actual ion hasn't been found to exist. — Argyll, Sep 06 '18 at 11:55
@Argyll He actually doesn't, at least not much. MO theory is the most advanced model and most 'correct' model of bonding that doesn't require advanced math to use. As such, it is widely used, even if often it is used to provide 'downgraded' description of model of higher level of theory. Thus, absolutely every advanced general chemistry and advanced organic chemistry textbooks uses MO theory at some point. — permeakra, Sep 06 '18 at 18:30
@permeakra: And that is not the majority of chemical literature in past decades. If such a claim was true, I expect to run into MO theory frequently in whatever random selection of chemistry literature. But obviously not. My interest actually isn't in chemistry now. I used to skim through papers broadly when I explored what topics I may like. In fact, I didn't run into MO at all. — Argyll, Sep 07 '18 at 19:53
If such a claim was true, I expect to run into MO theory frequently in whatever random selection of chemistry literature. || you actually would run into it a lot more often than into VSERP, which is of mostly historic interest. — permeakra, Sep 08 '18 at 11:50

score 3 · Answer 1 · edited Sep 05 '18 at 16:10

Most likely, the structure is a distorted octahedron. This means, that the electron structure of the compound can be derived from the orbital diagram of $\ce{XeF6}$ octahedron (see here What is the molecular structure of xenon hexafluoride?)

Electron count in $\ce{XeF6}$ and $\ce{[XeO6]^{3-}}$ differs by 3 electrons, so we have to remove three electrons from the diagram found in the reference. Thus, the HOMO are two orbitals of $e_\mathrm{g}$ symmetry populated by 3 electrons. When two orbitals of the same energy have different electron population, a Jahn-Teller distortion occurs. The orbitals of similiar symmetry with similar occupation can be found, for example, in $\ce{Cu^{2+}}$ compounds. They typically show a geometry of distorted octahedrons with 2 opposite ligands significantly further from the central atom, than the 4 other ligands.

So, with quick and dirty treatment suggests that there are 2 different bond lengths in the ion $\ce{[XeO6]^{3-}}$.

VSERP is unlikely to be of use in this case.

How many equal Xe–O bond length are present in (XeO_6)-3?

1 Answers1