Explanation

(d)
Ferrocene of bi-(cyclopentadienyl) iron is an orange-crystalline solid. It is $Fe\left( \eta^{5}–C_{5}H_{5} \right)_{2}$. The structure of ferrocene is regarded as sandwiche structure, in which the iron atom is sandwiched between two $C_{5}H_{5}$ organic rings. The planes of the rings are parallel so that all the carbon atoms are at the same distance from the iron atom.
It is a $\pi$-bonded complex. Its structure is as
[image:9_image234.emf]