Is XeO2F4 in the D4h Point Group?

[ochemnerd]

Homework Statement

Had this question on a test today and now I'm having second thoughts. We were asked to assign the point group of symmetry for the compound XeO2F4.

Homework Equations

None

The Attempt at a Solution

I had initially thought that it fell under D4h because it contains 1 C4 axis, 4 C2 axes, 4 σv planes and 1 σh plane. I know that the compound XeF4 is D4h and my rationale for assigning D4h to XeO2F4 was that it is identical to XeF4 except that instead of 2 lone pairs on the Xe there are 2 double bonded O's.

However, is the correct assignment for XeO2F4 octahedron (Oh)? It is a octahedral shape according to VSEPR but I'm not sure if all 6 substituents on the central atom have to be identical on Oh point groups.

Can someone please shed some light on this?

Cheers!

 

[sjb-2812]

Homework Statement

Had this question on a test today and now I'm having second thoughts. We were asked to assign the point group of symmetry for the compound XeO2F4.

Homework Equations

None

The Attempt at a Solution

I had initially thought that it fell under D4h because it contains 1 C4 axis, 4 C2 axes, 4 σv planes and 1 σh plane. I know that the compound XeF4 is D4h and my rationale for assigning D4h to XeO2F4 was that it is identical to XeF4 except that instead of 2 lone pairs on the Xe there are 2 double bonded O's.

However, is the correct assignment for XeO2F4 octahedron (Oh)? It is a octahedral shape according to VSEPR but I'm not sure if all 6 substituents on the central atom have to be identical on Oh point groups.

Can someone please shed some light on this?

Cheers!

yes, all 6 have to be the same. Don't forget there are also C3 axes in octahedral symmetry, which are not present in your proposed structure.

 

[ochemnerd]

Thanks for the clarification, sjb-2812!
I fail to see where the C3 axes would be though in a molecule of octahedral symmetry...

 

[sjb-2812]

Consider the shape at http://en.wikipedia.org/w/index.php?title=File:Octahedron.svg&page=1

Now, rotate one opposing pair of faces about an axis through their centres 120°...