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). This is one of the three common shapes for heptacoordinate transition metal complexes, along with the capped octahedron and the capped trigonal prism.
Pentagonal bipyramids are claimed to be promising coordination geometries for lanthanide-based single-molecule magnets, since they present no extradiagonal crystal field terms, therefore minimising spin mixing, and all of their diagonal terms are in first approximation protected from low-energy vibrations, minimising vibronic coupling.
Examples
- Iodine heptafluoride (IF7) with 7 bonding groups
- Rhenium heptafluoride (ReF7)
- Peroxo chromium(IV) complexes, e.g. [Cr(O2)2(NH3)3] where the peroxo groups occupy four of the planar positions.
- ZrF3−7 and HfF3−756
External links
- [1] – Images of IF7
- 3D Chem – Chemistry, Structures, and 3D Molecules
- IUMSC – Indiana University Molecular Structure Center
References
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 0-471-19957-5 ↩
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. /wiki/Inorganic_Chemistry_(journal) ↩
Wells, A. F. (1984). Structural Inorganic Chemistry (5th ed.). Oxford Science Publications. ISBN 0-19-855370-6. 0-19-855370-6 ↩
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. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9734471 ↩
Kaupp, Martin (2001). ""Non-VSEPR" Structures and Bonding in d0 Systems". Angewandte Chemie International Edition in English. 40 (1): 3534–3565. doi:10.1002/1521-3773(20011001)40:19<3534::AID-ANIE3534>3.0.CO;2-#. PMID 11592184. /wiki/Angewandte_Chemie ↩
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. /wiki/Inorganic_Chemistry_(journal) ↩