(i)
σ-bonded complexes Trimethyl aluminium is a
σ-bonded organometallic compound in which the metal and carbon atom of ligand are joined together with a
σ-bond. It exists at a dimer and two methyl group act as bridges between two aluminium atoms.
(ii)
π-complexes Zeise's salt and ferrocene are
π-bonded organometallic complexes. In these compounds, the
π-electrons of the organic compounds interact with the metal ions and thus occupy one of the coordination site.
K+[PtCl3(η2−C2H4)]Fe(η2−C5H5)2] Complexes with characteristics of both
σ-and
π-bonding In metal carbonyl
Cr(CO)6, the carbon of
CO donates a pair of electrons to the metal. The metal carbon bond in metal carbonyls has
σ as well as
π electrons.