Question

In which of the following pairs both the complexes show optical isomerism?

• A. cis$-[Cr(C_2 O_4 )_2 Cl_2 ]^{3-}, cis-[Co(NH_3 )_4 Cl_2 ]$
• B. $[Co(en)_3 ]Cl_3 , cis-[Co(en)_2 Cl_2 ]Cl$
• C. $[PtCl(dien)]Cl, [NiCl_2 Br_2 ]^{2-}$
• D. $[Co(NO_3 )_3 (NH_3)_3 ], cis-[Pt(en)_2 Cl_2 ]$

Answer 1

Answer: (B)

$[Co(en)_3 ]Cl_3 , cis-[Co(en)_2 Cl_2 ]Cl$

Answer 2

Both cis-[Co(en) $\left._{3}\right] Cl _{3}$ and cis-[Co(en) $\left._{2} Cl _{2}\right] Cl$ show optical isomerism. Optical isomers are non superimposable mirror images of each other. Compounds with co-ordination number $4$ and $6$ show optical isomerism.