Pentagonal bipyramidal molecular geometry

{{Short description|Molecular structure having atoms at the centre and corners of a pentagonal bipyramid}}

{{Infobox molecular geometry

| Examples= {{chem2|IF7}}, {{chem2|ZrF7(3-) }}

| Image_File=Pentagonal-bipyramidal-3D-balls.png

| Symmetry_group= D_5h

| Atom_direction= 7

| Bond_angle= 90°, 72°

| mu= 0

}}

Image:Iodine-heptafluoride-3D-vdW.png, 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 D_5h.

The pentagonal bipyramid is a case where bond angles surrounding an atom are not identical (see also trigonal bipyramidal molecular geometry).{{Cotton&Wilkinson6th}}{{Page needed|date=December 2024}} This is one of the three common shapes for heptacoordinate transition metal complexes, along with the capped octahedron and the capped trigonal prism.{{cite journal

| title = Seven-coordination. A molecular orbital exploration of structure, stereochemistry, and reaction dynamics

| author1 = Roald. Hoffmann

| author2 = Barbara F. Beier

| author3 = Earl L. Muetterties

| author4 = Angelo R. Rossi

| journal = Inorganic Chemistry

| year = 1977

| volume = 16

| issue = 3

| pages = 511–522

| doi = 10.1021/ic50169a002

}}{{cite book|last=Wells |first=A. F. |date=1984 |title=Structural Inorganic Chemistry |edition=5th |publisher=Oxford Science Publications |ISBN=0-19-855370-6}}{{Page needed|date=December 2024}}

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.{{Cite journal |last1=Duan |first1=Yan |last2=Rosaleny |first2=Lorena E. |last3=Coutinho |first3=Joana T. |last4=Giménez-Santamarina |first4=Silvia |last5=Scheie |first5=Allen |last6=Baldoví |first6=José J. |last7=Cardona-Serra |first7=Salvador |last8=Gaita-Ariño |first8=Alejandro |date=2022-12-09 |title=Data-driven design of molecular nanomagnets |journal=Nature Communications |language=en |volume=13 |issue=1 |pages=7626 |doi=10.1038/s41467-022-35336-9 |pmid=36494346 |pmc=9734471 |bibcode=2022NatCo..13.7626D |issn=2041-1723}}

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