In
chemistry,
octahedral molecular geometry describes the shape of compounds with six atoms or groups of atoms or
ligands symmetrically arranged around a central atom, defining the vertices of an octahedron. The
octahedron has eight faces, hence the
prefix octa. The octahedron is one of the
Platonic solids, although octahedral molecules typically have an atom in their centre and no bonds between the ligand atoms. A perfect
octahedron belongs to the
point group Oh. 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. For example,
[Co(NH3)6]3+, which is not octahedral in the mathematical sense due to the orientation of the N-H bonds, is referred to as octahedral.