Question

Which one of the following is expected to exhibit optical isomerism ? (en = ethylenediamine)

• A. cis - [Pt(NH₃)₃Cl₂]
• B. trans - [Pt(NH₃)₃Cl₂]
• C. cis - [Co(en)₂Cl₂]⁺
• D. trans - [Co(en)₂Cl₂]⁺

Answer 1

Answer: (C)

Optical isomerism is not shown by square planar complexes.
Octahedral complexes of general formulae,
${\left(\left[{\left(\text{Ma}\right)}_2{\left(\text{b}\right)}_2{\left(\text{c}\right)}_2\right]\right)}^{\text{n}\pm }\text{, }\left[\text{Mabcdf}\right]\text{, }{\left(\left[\text{M}{\left(\text{AA}\right)}_3\right]\right)}^{\text{n}\pm }\text{, }{\left(\left[\text{M}{\left(\text{AA}\right)}_2{\left(\text{a}\right)}_2\right]\right)}^{\text{n}\pm }$ (where AA = symmetrical bidentate ligand), ${\left(\left[\text{M}{\left(\text{AA}\right)}_2\text{ab}\right]\right)}^{\text{n}\pm }\text{ and }{\left(\left[\text{M}{\left(\text{AB}\right)}_3\right]\right)}^{\text{n}\pm }$ (where AB = unsymmetrical ligand) show optical isomerism.
does not show optical isomerism (superimposable mirror image). But cis - form shows optical isomerism.

cis - [Co(en)₂Cl₂]²⁺