Question

An example of a sigma bonded organometallic compound is:

• A. Ruthenocene
• B. Grignard's reagent
• C. Ferrocene
• D. Cobaltocene

Answer 1

The correct option is B Grignard's reagent

Grignard's reagent i.e., $R-Mg-X$ is a $\sigma$ -bonded organometallic compound.

The other three organometallic compounds have the metal ($Ru$ in Ruthenocene, $Fe$ in Ferrocene, $Co$ in cobaltocene) sandwiched betweeen two pentene rings. Pentene contains $\pi$ bonds and thus cannot be considered a $\sigma$ bonded organometallic compound.