Question

Explain optical isomerism in coordination compounds with an example.

Answer 1

1. Coordination compounds which possess chirality exhibit optical isomerism similar to organic compounds.

2. The pair of two optically active isomers which are mirror images of each other are called enantiomers.

3. Their solutions rotate the plane of the plane polarised light either clockwise or anticlockwise and the corresponding isomers are called d (dextrorotatory) and 1 (levorotatory) forms respectively.

4. The octahedral complexes of type [M(xx)₃]^n±, [M(xx)₂AB]^n± and [M(xx)₂B₂]^n± exhibit optical isomerism.

Examples:

1. The optical isomers of [Co(en)₃]³⁺ are shown below.

                               Optical isomer

2. The coordination complex [COCl₂(en)₂]⁺ has three isomers, two optically active cis forms and one optically inactive transform. These structures are shown below.

                                Optical isomers

3. In a coordination compound of type [PtCl₂(en)₂]²⁺, two geometrical isomers are possible. They are cis and trans. Among these two isomers, cis isomer shows optically active isomerism because the whole molecule is asymmetric.

                Optical isomers of Cis [PtCl₂(en)₂]²⁺