Choose the coordination compound which does not exhibit Optical activity.

Step-by-step solution

Optical activity in coordination compounds requires the absence of a plane of symmetry and a center of inversion. The complex [ Co ( en )₃ ]³⁺ is a tris-chelated octahedral complex which lacks both a plane of symmetry and a center of inversion, hence it is optically active. The complex cis - [ CoCl ₂( en )₂ ]⁺ lacks a plane of symmetry and a center of inversion, making it optically active. The complex cis - [ PtCl ₂( en )₂ ]²⁺ also lacks a plane of symmetry and a center of inversion, making it optically active. The