Pentagonal bipyramidal molecular geometry
ExamplesIF7, ZrF73−
Point groupD5h
Coordination number7
Bond angle(s)90°, 72°
μ (Polarity)0
Structure of iodine heptafluoride, an example of a molecule with the pentagonal-bipyramidal coordination geometry.

In chemistry, a pentagonal bipyramid is a molecular geometry with one atom at the centre with seven ligands at the corners of a pentagonal bipyramid. A perfect pentagonal bipyramid belongs to the molecular point group D5h.

The pentagonal bipyramid is a case where bond angles surrounding an atom are not identical (see also trigonal bipyramidal molecular geometry).[1] This is one of the three common shapes for heptacoordinate transition metal complexes, along with the capped octahedron and the capped trigonal prism.[2][3]

Pentagonal bipyramids are claimed to be promising coordination geometries for lanthanide-based single-molecule magnets, since (a) they present no extradiagonal crystal field terms, therefore minimising spin mixing, and (b) all of their diagonal terms are in first approximation protected from low-energy vibrations, minimising vibronic coupling.[4]



  1. ^ Cotton, F. Albert; Wilkinson, Geoffrey; Murillo, Carlos A.; Bochmann, Manfred (1999), Advanced Inorganic Chemistry (6th ed.), New York: Wiley-Interscience, ISBN 0-471-19957-5
  2. ^ Roald. Hoffmann; Barbara F. Beier; Earl L. Muetterties; Angelo R. Rossi (1977). "Seven-coordination. A molecular orbital exploration of structure, stereochemistry, and reaction dynamics". Inorganic Chemistry. 16 (3): 511–522. doi:10.1021/ic50169a002.
  3. ^ Wells A.F. (1984) Structural Inorganic Chemistry 5th edition Oxford Science Publications ISBN 0-19-855370-6
  4. ^ Duan, Yan; Rosaleny, Lorena E.; Coutinho, Joana T.; Giménez-Santamarina, Silvia; Scheie, Allen; Baldoví, José J.; Cardona-Serra, Salvador; Gaita-Ariño, Alejandro (2022-12-09). "Data-driven design of molecular nanomagnets". Nature Communications. 13 (1): 7626. Bibcode:2022NatCo..13.7626D. doi:10.1038/s41467-022-35336-9. ISSN 2041-1723. PMC 9734471. PMID 36494346.
  5. ^ Kaupp, Martin (2001). ""Non-VSEPR" Structures and Bonding in d(0) Systems". Angew Chem Int Ed Engl. 40 (1): 3534–3565. doi:10.1002/1521-3773(20011001)40:19<3534::AID-ANIE3534>3.0.CO;2-#. PMID 11592184.
  6. ^ Zhenyang Lin; Ian Bytheway (1996). "Stereochemistry of Seven-Coordinate Main Group and d0 Transition Metal Molecules". Inorganic Chemistry. 35 (3): 594–603. doi:10.1021/ic950271o.