Question

Which one of the following has an optical isomer?

• A. $\left[Zn\right(en\left)\right(N{H}_3{)}_2{]}^{2+}$
• B. $\left[Co\right(en{)}_3{]}^{3+}$
• C. $\left[Co\right(H_{2}O{)}_4\left(en\right){]}^{3+}$
• D. $\left[Zn\right(en{)}_2{]}^{2+}$ $(en=ethylenediamine)$

Answer 1

Answer: (B)

$\left[Co\right(en{)}_3{]}^{3+}$

$\left[Co\right(en{)}_3{]}^{3+}$ is optically active and will give rise to optical isomers. Six co-ordinate complexes containing three identical bidenate ligands, such as ${Co(en{)}_3}^{3+}$ or $CO(Ox{)}_5$ are optically active.