Which of the following coordination compounds would exhibit optical isomerism?

• A

  Pentaamminenitrocobalt(III) iodide
• B

  Diamminedichloroplatinum (II)
• C

  Trans dicyanobis(ethylenediamine) chromium(III) chloride
• Correct answer
  D

  Tris-(ethylenediamine) cobalt(III) bromide

Solution

$\left[\operatorname{Co}(\mathrm{en})_3\right]^{3+}$
Related Theory Optical isomerism occurs when a molecule is not superimposable with its mirror image. Structural isomers have the same chemical composition but the bonds are different.

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