Which of the following complex species is not expected to exhibit optical isomerism?

1. $\left[\text{Co}{\left({\text{NH}}_3\right)}_3{\text{Cl}}_3\right]$
2. ${\left[\text{Co}\left(\text{en}\right){\left({\text{NH}}_3\right)}_2{\text{Cl}}_2\right]}^{+}$
3. ${\left[\text{Co}\left(\text{en}\right){}_3\right]}^{3+}$
4. ${\left[\text{Co}\left(\text{en}\right){}_2{\text{Cl}}_2\right]}^{+}$

Solution

$\left[\text{Co}{\left({\text{NH}}_3\right)}_3{\text{Cl}}_3\right]$

${\text{MA}}_{\text{3}}{\text{B}}_{\text{3}}$ type compounds exhibit facial as well as meridional isomerism. Since both isomers have a plane of symmetry they do not exhibit optical isomerism.

Asked in: JEE Main 2013 (07 Apr)

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