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Symmetry Lab4AB · ABC Chemistry

Symmetry Lab › Oh › Octamethylsilsesquioxane, T₈ (methyl C shown)

Si₈O₁₂(CH₃)₈ Octamethylsilsesquioxane, T₈ (methyl C shown)

Cube of Si with O on every edge · point group Oh · order 48

Open Si₈O₁₂(CH₃)₈ in 3D →

Point group
Oh — The full symmetry of a regular octahedron or cube: three C4 axes, four C3 axes, six C2 axes, a centre of inversion and nine mirror planes.
Order
48
Operations
E, 8C₃, 6C₂′, 6C₄, 3C₂, i, 6S₄, 8S₆, 3σh, 6σd
Shape
Cube of Si with O on every edge
Atoms
28 (Si × 8, C × 8, O × 12)

Symmetry elements of Si₈O₁₂(CH₃)₈

  • C₄ (x) — through the centres of two opposite faces of the Si₈ cube
  • C₄ (y) — through the centres of two opposite faces of the Si₈ cube
  • C₄ (z) — through the centres of two opposite faces of the Si₈ cube
  • C₃ (1) — through two opposite Si corners
  • C₃ (2) — through two opposite Si corners
  • C₃ (3) — through two opposite Si corners
  • C₃ (4) — through two opposite Si corners
  • C₂′ (1) — through two opposite O atoms
  • C₂′ (2) — through two opposite O atoms
  • C₂′ (3) — through two opposite O atoms
  • C₂′ (4) — through two opposite O atoms
  • C₂′ (5) — through two opposite O atoms
  • C₂′ (6) — through two opposite O atoms
  • i — centre of inversion
  • σh (yz) — parallel to two faces, halfway between them
  • σh (xz) — parallel to two faces, halfway between them
  • σh (xy) — parallel to two faces, halfway between them
  • σd (1) — through two opposite edges
  • σd (2) — through two opposite edges
  • σd (3) — through two opposite edges
  • σd (4) — through two opposite edges
  • σd (5) — through two opposite edges
  • σd (6) — through two opposite edges
  • S₄ (x) — rotate 90°, then reflect
  • S₄ (y) — rotate 90°, then reflect
  • S₄ (z) — rotate 90°, then reflect
  • S₆ (1) — rotate 60°, then reflect
  • S₆ (2) — rotate 60°, then reflect
  • S₆ (3) — rotate 60°, then reflect
  • S₆ (4) — rotate 60°, then reflect

Structure

  • Si–O 1.62 Å, Si–C 1.85 Å
  • Si–O–Si ≈ 150°: the O atoms bow outwards from the cube edges
  • The smallest polyhedral silsesquioxane (POSS)
Octamethylsilsesquioxane, T₈ (methyl C shown) (Si8O12(CH3)8) — Oh symmetry elements
Octamethylsilsesquioxane, T₈ (methyl C shown): symmetry elements of the Oh point group

Other Oh molecules

[Co(NH₃)₆]³⁺ (N atoms shown)Hexaamminecobalt(III) ion[Fe(H₂O)₆]³⁺ (O atoms shown)Hexaaquairon(III) ion[PtCl₆]²⁻Hexachloroplatinate(IV) ion[AlF₆]³⁻Hexafluoroaluminate ion[SbF₆]⁻Hexafluoroantimonate ionPF₆⁻Hexafluorophosphate ionSiF₆²⁻Hexafluorosilicate ionSeF₆Selenium hexafluorideSF₆Sulfur hexafluorideUF₆Uranium hexafluoride[B₆H₆]²⁻closo-Hexahydridohexaborate ionCr(CO)₆Chromium hexacarbonyl

Open in the 3D lab →  ·  All Oh molecules  ·  All point groups