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Symmetry Lab4AB · ABC Chemistry

Symmetry Lab › D2d › Cyclo-octatetraene (tub)

C₈H₈ Cyclo-octatetraene (tub)

Tub · point group D2d · order 8

Open C₈H₈ in 3D →

Point group
D2d — A C2 principal axis, 2 perpendicular C2 axes and 2 dihedral mirror planes that bisect them; the principal axis is also an S4 axis.
Order
8
Operations
E, 2S₄, C₂, 2C₂′, 2σd
Shape
Tub
Atoms
16 (C × 8, H × 8)

Symmetry elements of C₈H₈

  • C₂ — through the centre of the tub
  • S₄ — rotate 90°, then reflect: swaps the up and down sides
  • C₂′ (1) — through the midpoints of two opposite double bonds
  • C₂′ (2) — through the midpoints of the other two
  • σd (1) — contains the axis, through two opposite single bonds
  • σd (2) — contains the axis, through the other two single bonds

Structure

  • C=C 1.34 Å, C–C 1.48 Å
  • Alternating single and double bonds
  • Not aromatic: the ring is a tub, not a plane
Cyclo-octatetraene (tub) (C8H8) — D2d symmetry elements
Cyclo-octatetraene (tub): symmetry elements of the D2d point group

Other D2d molecules

B₂Cl₄Diboron tetrachloride (gas phase)C₂H₄ (90° twisted)Ethylene, perpendicular (rotation transition state)C₃H₄Allene (propadiene)S₄N₄Tetrasulfur tetranitrideC₅H₈Spiropentane

Open in the 3D lab →  ·  All D2d molecules  ·  All point groups