Symmetry Lab › D4h › Octachlorodirhenate(III) ion
[Re₂Cl₈]²⁻ Octachlorodirhenate(III) ion
Two eclipsed ReCl₄ squares · point group D4h · order 16
- Point group
- D4h — A C4 principal axis, 4 perpendicular C2 axes and a horizontal mirror plane; these also give 4 vertical planes and a centre of inversion.
- Order
- 16
- Operations
- E, 2C₄, C₂, 2C₂′, 2C₂″, i, 2S₄, σh, 2σᵥ, 2σd
- Shape
- Two eclipsed ReCl₄ squares
- Atoms
- 10 (Re × 2, Cl × 8)
Symmetry elements of [Re₂Cl₈]²⁻
- C₄ — along the Re–Re bond
- C₂′ (x) — perpendicular to Re–Re, through two Cl on each Re
- C₂′ (y) — perpendicular to Re–Re, through the other Cl
- C₂″ (1) — perpendicular to Re–Re, between Cl atoms
- C₂″ (2) — perpendicular to Re–Re, between Cl atoms
- i — centre of inversion
- σh — perpendicular to Re–Re, through its midpoint
- σᵥ (xz) — contains Re–Re and four Cl
- σᵥ (yz) — contains Re–Re and the other four Cl
- σd (1) — contains Re–Re, between Cl atoms
- σd (2) — contains Re–Re, between Cl atoms
- S₄ — rotate 90°, then reflect in σh
Structure
- Re–Re 2.24 Å (quadruple bond), Re–Cl 2.29 Å
- The two ReCl₄ units are exactly eclipsed
- Cotton’s classic metal–metal quadruple bond
![Octachlorodirhenate(III) ion ([Re2Cl8]2-) — D4h symmetry elements](/molecular-symmetry/infographics/Re2Cl82-_OctachlorodirhenateIIIion_D4h.png)
Other D4h molecules
[Pt(NH₃)₄]²⁺ (N atoms shown)Tetraammineplatinum(II) ion[AuCl₄]⁻Tetrachloroaurate(III) ion[ICl₄]⁻Tetrachloroiodate(III) ion[PdCl₄]²⁻Tetrachloropalladate(II) ion[PtCl₄]²⁻Tetrachloroplatinate(II) ion[BrF₄]⁻Tetrafluorobromate(III) ionXeF₄Xenon tetrafluoridetrans-[CoCl₂(NH₃)₄]⁺trans-Tetraamminedichlorocobalt(III) (N atoms shown)C₄H₄²⁻Cyclobutadiene dianion (planar)[Ni(CN)₄]²⁻Tetracyanonickelate(II) ion[Pt(CN)₄]²⁻Tetracyanoplatinate(II) iontrans-[OsCl₂(CO)₄]trans-Dichlorotetracarbonylosmium(II)