# What are the structures of potassium superoxide and xenon hexafluoride? [closed]

I have 2 questions in mind:

1) What is the structure of the superoxides? More specifically, what is the structure of $\ce{KO_2}$?

2) What is the structure of and dipole moment for $\ce{XeF_6}$?

• Welcome to chemistry.SE. If you have two questions then please post them as separate questions, not together in the same post. Also please add a bit more detail and your thoughts about the problem to make us sure we aren't doing your homework for you.
– bon
Jul 16 '15 at 15:16
• @ToddMinehardt I assume you are very familiar with LaTeX syntax ;) We have this neat package called mhchem installed, which makes typesetting chemical formulae much easier. You can have a look at some meta posts to learn more: this one and this one. Thanks for helping out :D Jul 17 '15 at 7:17

Xenon hexafluoride's geometry is not easy to be described but it is assumed to be in $C_{3v}$-symmetry - not octahedral! - in gas phase which is supported by electron diffraction measurements and quantum chemical calculations. It crystallizes in at least six to seven different known structures. [1]

As it is further written

Konrad Seppelt, an authority on noble gas and fluorine chemistry, says, "the structure is best described in terms of a mobile electron pair that moves over the faces and edges of the octahedron and thus distorts it in a dynamic manner."

On you question regarding the dipole moment - for the $C_{3v}$-symmetry $\ce{XeF6}$ the dipole moment is calculated to be $0.46~\mathrm{D}$. [2]

The structure of $\ce{KO2}$ can also be found on wikipedia. There you find the following picture, showing it in it's body-centered cubic unit cell.

• Computed dipole moments for 3 symmetries here gives 0.46 D for $C_{3v}$. Jul 16 '15 at 15:41
• It would be very nice, if you could provide the complete reference when pointing to articles. This way we can be sure that the quotation can be found even if the pages/links change. And I am very surprised about the structure of xenon hexaflouride. Jul 16 '15 at 16:51
• T. D. Crawford, K. W. Springer, and H. E. Schaeffer III. "A contribution to the understanding of the structure of xenon hexafluoride." J. Chem. Phys. 102, 3307 (1995). Jul 16 '15 at 22:29