Question

Which of the following does not have optical isomer?

• A. $\left[ Co \left( NH _{3}\right)_{3} Cl _{3}\right]$
• B. $\left[ Co ( en )_{3}\right]^{3+}$
• C. $\left[ Co ( en )_{2} Cl _{2}\right] Cl$
• D. $\left[ Co ( en )\left( NH _{3}\right)_{2} Cl _{2}\right] Cl$

Answer 1

Answer: (A)

$\left[ Co \left( NH _{3}\right)_{3} Cl _{3}\right]$

Answer 2

Octahedral complexes of type $\left[M a_{2} b_{2} c_{2}\right]$, $[M a b c d e f],\left[M(A A)_{3}\right],\left[M(A A)_{2} a_{2}\right]$, $\left[M(A A) a_{2} b_{2}\right],\left[M(A A)_{2} a b\right]$ and $\left[M(A B)_{3}\right]$ show optical isomerism due to asymmetric molecules. Octahedral complexes of type $\left[M a_{4} b_{2}\right]$ and $\left[ Ma _{3} b _{3}\right]$ do not show optical isomerism due to presence of plane of symmetry. Hence $\left[ Co ( NH )_{3} Cl _{3}\right]$ will not show optical isomerism.