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Homework Help: Assigning Point Group for XeO2F4

  1. Oct 12, 2012 #1
    1. The problem statement, all variables and given/known data
    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.

    2. Relevant equations

    3. 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?

  2. jcsd
  3. Oct 13, 2012 #2
    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.
  4. Oct 13, 2012 #3
    Thanks for the clarification, sjb-2812!
    I fail to see where the C3 axes would be though in a molecule of octahedral symmetry...
  5. Oct 13, 2012 #4
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