Question

Both geometrical and optical isomerism are exhibited by :-

• A. Dichlorobis (ethylenediamine) cobalt $\left(III\right)$ ion
• B. Pentaamminechlorocobalt $\left(III\right)$
• C. Triamminotrichlorocoblat $\left(III\right)$ ion
• D. Tetraamminedichlorocoblat $\left(III\right)$ ion

Answer 1

Answer: (A)

The geometric isomers of ${\left[Co{\left(en\right)}_2{\left(Cl\right)}_2\right]}^{+}$ are shown below. Two isomers cis- and trans- forms are possible for this compound. The $en$ ligand donates the ethylene diamine ligand. It is a bidentate ligand. Here the nitrogen atoms donate their lone pairs to form a bond. Since there are two ligands of each type available, we can say that cis and trans isomers are possible for this complex. They are as follows:

Optical isomerism of the compound is found in the cis-isomer in dextro and laevo. We know that we do not usually see optical isomerism in trans-isomers due to the existence of the plane of symmetry.