Question

In $Fe(CO{)}_5$ the $Fe-C$ bond has:

• A. Sigma character
• B. $\pi$ character
• C. Both $\sigma$ and $\pi$ character.
• D. Cannot predict

Answer 1

The correct option is C Both $\sigma$ and $\pi$ character.

In $Fe(CO{)}_5$, the oxidation state of $Fe$ is 0. So the number of valence electrons in $Fe$ is more. Again $CO$ has vaccant anti bonding ${\pi }^{\ast }$ orbital. Thus $CO$ is a very good $\pi$ accepting ligand. Thus here back bonding is also takes place . Hence the $Fe-C$ bond has both $\sigma$ and $\pi$ character.