In
chemistry
Chemistry is the science, scientific study of the properties and behavior of matter. It is a natural science that covers the Chemical element, elements that make up matter to the chemical compound, compounds made of atoms, molecules and ions ...
, 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). 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
The lanthanide () or lanthanoid () series of chemical elements comprises the 15 metallic chemical elements with atomic numbers 57–71, from lanthanum through lutetium. These elements, along with the chemically similar elements scandium and yttr ...
-based
Single-molecule magnets, since (a) they present no
extradiagonal Crystal Field Crystal field theory (CFT) describes the breaking of degeneracies of electron orbital states, usually ''d'' or ''f'' orbitals, due to a static electric field produced by a surrounding charge distribution (anion neighbors). This theory has been used ...
terms, therefore minimising spin mixing, and (b) all of their diagonal terms are in first approximation protected from low-energy vibrations, minimising
vibronic coupling.
Examples
*
Iodine heptafluoride (IF
7) with 7 bonding groups
*
Peroxo chromium
Chromium is a chemical element with the symbol Cr and atomic number 24. It is the first element in group 6. It is a steely-grey, lustrous, hard, and brittle transition metal.
Chromium metal is valued for its high corrosion resistance and hardne ...
(IV) complexes, e.g.
r(O2)2(NH3)3where the peroxo groups occupy four of the planar positions.
* and
References
External links
– Images of IF
7
3D Chem– Chemistry, Structures, and 3D Molecules
IUMSC– Indiana University Molecular Structure Center
{{MolecularGeometry
Stereochemistry
Molecular geometry