Which geometries can occur in coordination compounds with seven ligands?

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Structural diagram of the vitamin B12 coenzyme molecule, highlighting its organometallic core with five nitrogen-cobalt bonds and one cobalt-carbon bond at the center, surrounded by complex organic groups. — coordination compound Coordination compounds contain a central metal atom surrounded by nonmetal atoms or groups of atoms, called ligands. For example, vitamin B₁₂ is made up of a central metallic cobalt ion bound to multiple nitrogen-containing ligands.

In coordination chemistry, coordination compounds with a coordination number of seven can exhibit three primary geometric structures:

Pentagonal bipyramid: A structure where five ligands form a pentagonal plane around the central metal, with the remaining two ligands positioned above and below this plane.1
Capped trigonal prism: A geometry derived from a trigonal prism where an additional ligand is placed (capped) on one of the rectangular faces.1
Capped octahedron: A geometry derived from an octahedral structure where an additional ligand is placed (capped) on one of the triangular faces.1

These geometries are determined by factors such as the relative sizes of the metal and ligands, spatial constraints, and the electronic configuration of the metal ion.1