Capped square antiprismatic molecular geometry

In <a href="/facts/Chemistry/SrNqkGVm">chemistry</a>, the capped square antiprismatic molecular geometry describes the shape of compounds where nine atoms, groups of atoms, or <a href="/facts/Ligand/6etB3qeW">ligands</a> are arranged around a central atom, defining the vertices of a <a href="/facts/Gyroelongated_square_pyramid/urK5SXYc">gyroelongated square pyramid</a>. The <a href="/facts/Symmetry_group/CNqeseMp">symmetry group</a> of the resulting object is C4v.
The gyroelongated square pyramid is a <a href="/facts/Square_pyramid/wDetDohM">square pyramid</a> with a <a href="/facts/Square_antiprism/4514Q02s">square antiprism</a> connected to the square base. In this respect, it can be seen as a "capped" square antiprism (a square antiprism with a pyramid erected on one of the square faces).
It is very similar to the <a href="/facts/Tricapped_trigonal_prismatic_molecular_geometry/klxVT8AG">tricapped trigonal prismatic molecular geometry</a>, and there is some dispute over the specific geometry exhibited by certain molecules.
Examples:

<ul><li>[SiCo9(CO)21]2-, defined by the Co9 framework, which encapsulates the Si atom</li>
<li>[Pb(phen)4(OClO3)]+, defined by the N8O framework, which encapsulates the Pb2+ ion</li>
<li>[Ge9]4−, a <a href="/facts/Zintl_ion/EsuLgxJU">zintl ion</a></li>
<li>Th(<a href="/facts/Tropolone/mv7CLpKm">troopolonate</a>)4(H2O), defined by the O9 framework, which encapsulates the Th4+ ion</li>
<li><a href="/facts/Potassium_nonahydridorhenate/txc43N4W">ReH2−9</a> is sometimes described as having a capped square antiprismatic geometry, although its geometry is most often described as tricapped trigonal prismatic.</li>
<li>[LaCl(H2O)7]4+2, a <a href="/facts/Lanthanum/Uhmmy1sB">lanthanum</a>(III) complex with a La–La bond.</li></ul>

Capped square antiprismatic molecular geometry open-in-new

Capped square antiprismatic molecular geometry