Question

Which one of the following complexes shows optical isomerism?

• A. $\left[Co\right(N{H}_3{)}_{4}C{l}_2]Cl$
• B. $\left[Co\right(N{H}_3{)}_{3}C{l}_3]$
• C. $cis\left[Co\right(en{)}_{2}C{l}_2]Cl$
• D. trans $\left[Co\right(en{)}_{2}C{l}_2]Cl$

Answer 1

The correct option is C $cis\left[Co\right(en{)}_{2}C{l}_2]Cl$

Complex $\left[Co\right(N{H}_3{)}_{4}C{l}_2]Cl$ have two G.l. which are optically inactive due to presence of plane of symmetry.

Complex $\left[Co\right(N{H}_3{)}_{3}C{l}_3]$ also have two optically inactive geometrical isomers due to presence of plane of symmetry. $\left[Co\right(N{H}_3{)}_{3}C{l}_3]$ shows facial as well as meridional isomerism.

Complex cis $\left[Co\right(en{)}_{2}C{l}_2]Cl$ is optically active due to formation of non-super imposable mirror image.
Complex trans $\left[Co\right(en{)}_{2}C{l}_2]Cl$ is optically inactive. (en=ethylenediamine)