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A perfect octahedron belongs to the point group O h. Examples of octahedral compounds are sulfur hexafluoride SF 6 and molybdenum hexacarbonyl Mo(CO) 6 . The term "octahedral" is used somewhat loosely by chemists, focusing on the geometry of the bonds to the central atom and not considering differences among the ligands themselves.
Structural distortion analysis Determination of regular and irregular distorted octahedral molecular geometry; Octahedral distortion parameters [5] [6] [7] Volume of the octahedron; Tilting distortion parameter for perovskite complex [8] Molecular graphics. 3D modelling of complex; Display of the eight faces of octahedron
A regular octahedron has 24 rotational (or orientation-preserving) symmetries, and 48 symmetries altogether. These include transformations that combine a reflection and a rotation. A cube has the same set of symmetries, since it is the polyhedron that is dual to an octahedron.
The metal atoms define the vertices of an octahedron. The overall point group symmetry is O h. Each face of the octahedron is capped with a chalcohalide and eight such atoms are at the corners of a cube. For this reason this geometry is called a face capped octahedral cluster. Examples of this type of clusters are the Re 6 S 8 Cl 6 4− anion.
(To some extent rotation influences the geometry via Coriolis forces and centrifugal distortion, but this is negligible for the present discussion.) In addition to translation and rotation, a third type of motion is molecular vibration , which corresponds to internal motions of the atoms such as bond stretching and bond angle variation.
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The Jahn–Teller effect (JT effect or JTE) is an important mechanism of spontaneous symmetry breaking in molecular and solid-state systems which has far-reaching consequences in different fields, and is responsible for a variety of phenomena in spectroscopy, stereochemistry, crystal chemistry, molecular and solid-state physics, and materials science.
A normal abelian subgroup has distortion determined by the eigenvalues of the conjugation overgroup representation; formally, if g ∈ G acts on V ≤ G with eigenvalue λ, then V is at least exponentially distorted with base λ. For many non-normal but still abelian subgroups, the distortion of the normal core gives a strong lower bound. [1]