An example of a sigma bonded organometallic compound is:

Organometallic compounds involve a direct metal-carbon bond.Grignard reagents ($R-Mg-X$) have a $\sigma$ -bond between the carbon atom and the magnesium atom.Ferrocene, Cobaltocene, and Ruthenocene are "sandwich" compounds involving $\pi$ -bonding between the metal and the aromatic rings.