Question

Complex compound(s) which is optical active and does not depend upon the orientation of the ligands around metal cation:
(i) $\left[CoC{l}_3\right(N{H}_3{)}_3]$
(ii) $\left[Co\right(en{)}_3]C{l}_3$
(iii) $\left[Co\right(C_2{O}_4{)}_2(N{H}_3{)}_2{]}^{-}$
(iv) $\left[CrC{l}_2\right(N{H}_3{)}_2\left(en\right){]}^{+}$.

• A. (ii), (iii) and (iv)
• B. (i), (ii) and (iv)
• C. (ii) and (iv)
• D. only (ii)

Answer 1

The correct option is D only (ii)

In the complex $\left[CoC{l}_2\right(N{H}_3{)}_3]$, both cis and trans isomers are optically inactive.
The complex $\left[Co\right(en{)}_3]C{l}_3$ is optically active. It exists in d and l forms.
The asymmetry of the complex is not dependent on the orientation of the ligands.
The cis isomer of $\left[Co\right(C_2{O}_4{)}_2(N{H}_3{)}_2{]}^{-}$ is optically active whereas trans isomer is optically inactive.
Thus the asymmetry of the complex depends on the orientation of ammonia ligand.
In the complex $\left[CrC{l}_2\right(N{H}_3{)}_2\left(en\right){]}^{+}$, the cis form is optically active and one of the trans form is optically inactive and the other trans form is optically active.