In chemistry, the trigonal prismatic molecular geometry describes the shape of compounds where six atoms, groups of atoms, or

ligand In coordination chemistry, a ligand is an ion or molecule ( functional group) that binds to a central metal atom to form a coordination complex. The bonding with the metal generally involves formal donation of one or more of the ligand's ele ...

s are arranged around a central atom, defining the vertices of a

triangular prism In geometry, a triangular prism is a three-sided prism; it is a polyhedron made of a triangular base, a translated copy, and 3 faces joining corresponding sides. A right triangular prism has rectangular sides, otherwise it is ''oblique''. ...

Examples

Hexamethyltungsten (W(CH₃)₆) was the first example of a molecular trigonal prismatic complex. The figure shows the six carbon atoms arranged at the vertices of a triangular prism with the tungsten at the centre. The hydrogen atoms are not shown. Some other

transition metal In chemistry, a transition metal (or transition element) is a chemical element in the d-block of the periodic table (groups 3 to 12), though the elements of group 12 (and less often group 3) are sometimes excluded. They are the elements that c ...

s have trigonal prismatic hexamethyl complexes, including both neutral molecules such as Mo(CH₃)₆ and Re(CH₃)₆ and ions such as and . The complex Mo(S−CH=CH−S)₃ is also trigonal prismatic, with each S−CH=CH−S group acting as a bidentate ligand with two sulfur atoms binding the metal atom. Here the coordination geometry of the six sulfur atoms around the molybdenum is similar to that in the extended structure of molybdenum disulfide (MoS₂).

References

{{MolecularGeometry Stereochemistry Molecular geometry