Question

An example of a sigma bonded organometallic compound is

<!--td {border: 1px solid #ccc;}br {mso-data-placement:same-cell;}--> NEET-2017

Answer 1

The organometallic compounds having sigma bond between carbon and metal are sigma bonded organomettalic. An example of a sigma bonded organometallic compound is Grignard's reagent.
$\underset{\sigma -bond}{\underset{}{R-Mg-X}}$



The ferrocene compound contains the two $Fe-\left(C_2{H}_5\right)$ bonds. This Fe is sandwiched between the two cyclopentadienyl ligands. This is a pi bonded system. The plane of the rings is the same distance from the iron atom. Here, the Fe is bonded to the pi bond system thus the ferrocene is π− bonded organometallic compound.
The Cobaltocene, $Co(C_5{H}_5{)}_2$ and Ruthenocene, $Rh(C_5{H}_5{)}_2$ have a similar structure to the ferrocene. So, Cobaltocene and Ruthenocene are also π− bonded organometallic compounds.

Hence, option (b) is correct.