Question

Out of the following two coordination entities which is chiral (optically active)?

$A)$ $cis-\left[CrC{l}_2\right(ox{)}_2{]}^{3-}$

$B)$ $trans-\left[CrC{l}_2\right(ox{)}_2{]}^{3-}$

Answer 1

$\text{Optical isomers}$

Compounds which are non-superimposable mirror images of each other, are known as optical isomers.

$\text{Condition of optical activity}$

$\Rightarrow$ Molecule should not contain any symmetric elements like $\text{POS}$ (Plane of symmetry), $\text{COS}$ (Centre of symmetry).

In the given case,

For trans isomer, plane of symmetry is present. So, it optical inactive but in case of cis isomer there is no plane of symmetry, so it is optical active.

$\text{Optical active or inactive isomer}$

Optical active or inactive isomer are shown below:


$\text{Optical active or inactive isomer}$

Optical active or inactive isomer are shown below:


Hence, out of the two options, option $\left(a\right)cis-{\left[CrC{l}_2\right(ox{)}_2]}^{3-}$ is chiral (optically active).