Q62 / 180 · AIIMS 2004 · Chemistry

Which of the following does not have optical isomer?

  • Correct answer
    A
    $\left[\mathrm{Co}\left(\mathrm{NH}_3\right)_3 \mathrm{Cl}_3\right]$
  • B
    $\left[\mathrm{Co}(\mathrm{en})_3\right] \mathrm{Cl}_3$
  • C
    $\left[\mathrm{Co}(\mathrm{en})_2 \mathrm{Cl}_2\right] \mathrm{Cl}$
  • D
    $\left[\mathrm{Co}(\mathrm{en})\left(\mathrm{NH}_3\right)_2 \mathrm{Cl}_2\right] \mathrm{Cl}$

Solution

Optical isomerism is very common in octahedral complexes of general formulae, $\left[M a_2 b_2 c_2\right]^{n \pm},[M a b c d e f],\left[M(A A)_3\right]^{n \pm},\left[M(A A)_2 a_2\right]^{n \pm}$, $\left[M(A A) a_2 b_2\right]^{n \pm},\left[M(A A)_2 a b\right]^{n \pm}$ and $\left[M(A B)_3\right]^{n \pm}$, where $A A$ is symmetrical bidentate ligand and $A B$ is unsymmetrical bidentate ligand. Octahedral complex of the type $M a_4 b_2$ and $M a_3 b_3$ exhibit geometrical isomerism.

Hence, the correct answer is option: 'A'.

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