Which of the following does not show optical isomerism? (en = ethylenediamine)

Step-by-step solution

Optical isomerism is exhibited by only those complexes in which elements of symmetry are absent. Octahedral complexes of the types [ M ( aa )₃ ], [ M ( aa ) x ₂, y ₂ ] and [ M ( aa )₂ x ₂ ] have absence of elements of symmetry, thus exhibit optical isomerism. Here, a a represents bidentate ligand, x or y represents monodentate ligand and M represents central metal ion. Hence, [ Co ( NH ₃ )₃ Cl ₃ ]^0 due to presence of symmetry elements does not exhibit optical isomerism.