Page "Coordination complex" Paragraph 11

Different ligand structural arrangements result from the coordination number.

Most structures follow the points-on-a-sphere pattern ( or, as if the central atom were in the middle of a polyhedron where the corners of that shape are the locations of the ligands ), where orbital overlap ( between ligand and metal orbitals ) and ligand-ligand repulsions tend to lead to certain regular geometries.

The most observed geometries are listed below, but there are many cases that deviate from a regular geometry, e. g. due to the use of ligands of different types ( which results in irregular bond lengths ; the coordination atoms do not follow a points-on-a-sphere pattern ), due to the size of ligands, or due to electronic effects ( see, e. g., Jahn-Teller distortion ):