Hexagonal antiprism, bicapped

Hexagonal antiprism Bicapped pentagonal prism Anticuboctahedron... 

For n = 14 the second best polyhedron according to the calculations, the omnicapped cube, is realized rather than the more favoured bicapped hexagonal antiprism. This second best polyhedron is observed for both [Co6(CO)14]4- and [Co4Ni2(CO)14]2. ... 

Bicapped hexagonal antiprism C2BioHi2(CoCp)2 C4B8H8(FeCp)2... 

Structure Before [...] 0 (isolated), 2x0 (dimer), 3x0 (trimer), 4x0 (tetramer), 5x0 (pentamer), 1 (chain), 2 x 1 (double chain), 2 (layer). Inside [...] O (octahedron), TP (trigonal prism), CTP (capped trigonal prism), BCHAP (bicapped hexagonal antiprism), C (cube), SAP (square antiprism), T (transition metal as endohedral atom), 6, 7, 8 (number of cluster atoms), 8, 12, X (number of ligands). After [...] C (cubic), T (tetragonal), O (orthorhombic), M (monoclinic)... 

Three other forms of octacoordination, which occur less often and are essentially restricted to actinide and lanthanide compounds, are the hexagonal bipyramid (D6h) (1-VI), the bicapped trigonal prism (D3 ) (1-VII) and the bicapped trigonal antiprism (Dm) (1-VIII). The hexagonal bipyramid is restricted almost entirely to the oxo ions, where an OMO group defines the axis of the bipyramid, though it is occasionally found elsewhere. 

---