Tricapped trigonal prismatic molecular geometry

In chemistry, the tricapped trigonal prismatic molecular geometry describes the shape of compounds where nine atoms, groups of atoms, or ligands are arranged around a central atom, defining the vertices of a triaugmented triangular prism (a trigonal prism with an extra atom attached to each of its three rectangular faces).^[1]

Tricapped trigonal prismatic molecular geometry
Examples	ReH2− 9
Point group	D3h
Coordination number	9
μ (Polarity)	0

It is very similar to the capped square antiprismatic molecular geometry, and there is some dispute over the specific geometry exhibited by certain molecules.^{[citation needed]}

Examples

• ReH²⁻
  ₉^[2]
• Ln(H
  ₂O)³⁺
  ₉ (Ln = La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy)
• Th(H
  ₂O)⁴⁺
  ₉

References

1. "4.1.4: Coordination Numbers and Structures". Chemistry LibreTexts. 2021-12-20. Retrieved 2024-02-02.
2. Holleman, A. F.; Wiberg, Egon; Wiberg, Nils; Eagleson, Mary; Brewer, William; Aylett, Bernhard J., eds. (2001). Holleman-Wiberg inorganic chemistry. San Diego, Calif. London: Academic. ISBN 978-0-12-352651-9.