The polyhedral symbol indicates the geometrical arrangements of the
coordinating atoms about the
central atom. It consists of one or more
capital italic letters derived from common geometric terms
(tetrahedron, square plane, octahedron, etc.) which denote the
idealised geometry of the
ligands around the
coordination centre, and
an arabic numeral that is the
coordination number of the
central atom.
The polyhedral symbol is used as an affix, enclosed in parentheses,
and separated from the name by a hyphen. Examples are
T-4,
SP-4,
TBPY-5,
SPY-5,
OC-6, and
CU-8.
Source:
PAC, 1997, 69, 1251
(Glossary of terms used in bioinorganic chemistry (IUPAC Recommendations 1997))
on page 1292