Question

Which of the following are $\pi$ bonded organometallic compounds?
A.Ferrocene
B.Diethyl zinc
C.Ethyl magnesium iodide
D.Tetraethyl lead

Answer 1

Organometallic compounds are the compounds that consist of a metal atom along with the organic groups like alkyl groups or cyclic rings. The organometallic compounds with $\pi$ bonds are known as $\pi$ bonded organometallic compounds. Ferrocene consists of two pentadiene rings.

Complete answer:
Organic compounds are the chemical compounds that consist of only carbon and hydrogen atoms. Organometallic compounds are the compounds that consist of only organic groups and metal atoms. The metal atoms are zinc, magnesium, iron and lead.
Diethyl zinc is an organometallic compound with the presence of zinc and two ethyl groups. The bonds involved are only sigma bonds. Thus, it is an example of sigma bonded organometallic compounds.
Ethyl magnesium iodide is an organometallic compound with the presence of magnesium, iodine and two ethyl groups. The bonds involved are only sigma bonds. Thus, it is an example of sigma bonded organometallic compounds.
Tetraethyl lead is an organometallic compound with the presence of lead and four ethyl groups. The bonds involved are only sigma bonds. Thus, it is an example of sigma bonded organometallic compounds.
Ferrocene is an organometallic compound with the presence of iron and two pentadiene rings. The bonds involved are both sigma and pi bonds. Thus, it is an example of $\pi$ bonded organometallic compounds.
So, option (A) is the correct answer.

Note:
Sigma bonds are the strong bonds that are formed from the lateral overlap of orbitals. Pi bonds are the strong bonds that are formed from the sideways overlap of orbitals. Ferrocene consists of two pentadiene rings; each ring has two pi bonds and is considered as $\pi$ bonded organometallic compounds.