State the $IUPAC$ name of the following complex: $Fe(C_5H_5)_2$.

Given below are two statements: one is labelled as Assertion $(A)$ and the other is labelled as Reason $(R)$.
Assertion $(A)$: The metal-carbon bond in metal carbonyls possesses both $\sigma$ and $\pi$ character.
Reason $(R)$: The ligand-to-metal bond is a $\sigma$ bond and metal-to-ligand bond is a $\pi$ bond.
In the light of the above statements,choose the most appropriate answer from the options given below :

Which of the following organometallic compounds is both $\sigma$ and $\pi$ bonded?

Which of the following does not have a metal-carbon bond?

Which of the following is not considered as an organometallic compound?

What are organometallic compounds? Explain in detail.