Symmetry Lab › D8h › Cyclo-octatetraene dianion (planar)
C₈H₈²⁻ Cyclo-octatetraene dianion (planar)
Planar 8-membered ring · point group D8h · order 32
- Point group
- D8h — A C8 principal axis, 8 perpendicular C2 axes and a horizontal mirror plane; these also give 8 vertical planes and a centre of inversion.
- Order
- 32
- Operations
- E, 2C₈, 2C₈³, 2C₄, C₂, 4C₂′, 4C₂″, i, 2S₈, 2S₈³, 2S₄, σh, 4σᵥ, 4σd
- Shape
- Planar 8-membered ring
- Atoms
- 16 (C × 8, H × 8)
Symmetry elements of C₈H₈²⁻
- C₈ — perpendicular to the ring
- C₂′ (1) — in the plane, through two opposite atoms
- C₂′ (2) — in the plane, through two opposite atoms
- C₂′ (3) — in the plane, through two opposite atoms
- C₂′ (4) — in the plane, through two opposite atoms
- C₂″ (1) — in the plane, through two opposite bond midpoints
- C₂″ (2) — in the plane, through two opposite bond midpoints
- C₂″ (3) — in the plane, through two opposite bond midpoints
- C₂″ (4) — in the plane, through two opposite bond midpoints
- i — centre of inversion
- σh — the plane of the ring
- σᵥ (1) — perpendicular to the plane, through two opposite atoms
- σᵥ (2) — perpendicular to the plane, through two opposite atoms
- σᵥ (3) — perpendicular to the plane, through two opposite atoms
- σᵥ (4) — perpendicular to the plane, through two opposite atoms
- σd (1) — perpendicular to the plane, through two opposite bond midpoints
- σd (2) — perpendicular to the plane, through two opposite bond midpoints
- σd (3) — perpendicular to the plane, through two opposite bond midpoints
- σd (4) — perpendicular to the plane, through two opposite bond midpoints
- S₈ — rotate 45°, then reflect in σh
Structure
- C–C 1.41 Å (all equal)
- Ten π electrons: aromatic and planar
- The neutral tub (D2d) flattens on taking two electrons
