An affix giving a topological indication of the bonding between a π-electron ligand
and the
central atom in a
coordination entity. A right superscript numerical index indicates the number of ligating atoms in the
π-electron system of the ligand which bind to the
central atom.
Examples:
- [Fe(CO)3(C4H6SO)],
tricarbonyl(η2-dihydrothiophene 1-oxide-κO)iron.
- [Cr(CO)4(C4H6)],
tetracarbonyl(η4-2-methylene-1,3-propanediyl)chromium.
Source:
See also:
Blue Book, p. 465
PAC, 1994, 66, 1077
(Glossary of terms used in physical organic chemistry (IUPAC Recommendations 1994))
on page 1120