Question

$\left[ Co{{\left( N{{H}_{3}} \right)}_{4}}C{{l}_{2}} \right]N{{O}_{2}}$ and $\left[ Co{{\left( N{{H}_{3}} \right)}_{4}}Cl\ N{{O}_{2}} \right]Cl$ are _____________ isomers.
A) Geometrical
B) Optical
C) Linkage
D) Ionization

Answer 1

Hint: A type of structural isomerism can be observed in the coordination complexes when the anions or the neutral atoms exchange the ligands initially present within the coordination sphere. This type of isomerism may result in the dissociation of different ions in the aqueous solution.

Complete answer:Ionization isomerism: It is a type of structural isomerism which is observed when the anion or the neutral atom which was present initially outside the coordination sphere replaces the ligands present within the coordination sphere. This may result in a change in the charge of counterions and the coordination sphere and thus is termed as ionization isomerism. The complexes showing this isomerism are known as Ionization isomers.

Some of the examples of Ionization isomerism are as follows:

1. $\left[ Co{{\left( N{{H}_{3}} \right)}_{5}}Br \right]S{{O}_{4}}\,\,\And \,\,\,\left[ Co{{\left( N{{H}_{3}} \right)}_{5}}S{{O}_{4}} \right]Br\,$

2. $\left[ Co{{\left( N{{H}_{3}} \right)}_{4}}C{{l}_{2}} \right]N{{O}_{2}}\,\,\And \,\,\,\left[ Co{{\left( N{{H}_{3}} \right)}_{4}}N{{O}_{2}}Cl \right]Cl\,$

3. $\left[ Co{{\left( N{{H}_{3}} \right)}_{5}}N{{O}_{3}} \right]S{{O}_{4}}\,\,\And \,\,\,\left[ Co{{\left( N{{H}_{3}} \right)}_{5}}S{{O}_{4}} \right]N{{O}_{3}}\,$

In simple words, we can say that the coordination complex which has similar molecular composition but then also they give different ions upon dissolving the complex in the aqueous solution. Ionization isomerism is one of the forms of isomerism that can relate to the way in which the ligands are bonded with the central metal ion within the coordination complex.

Thus, as per the complexes given in the question, $\left[ Co{{\left( N{{H}_{3}} \right)}_{4}}C{{l}_{2}} \right]N{{O}_{2}}$ and $\left[ Co{{\left( N{{H}_{3}} \right)}_{4}}Cl\ N{{O}_{2}} \right]Cl$ are ionization isomers. Hence, option (D) is the correct answer.

Note: It is important to note that Ionization isomerism in complexes arises when the counterion present within the complex has the tendency or potential to exchange the ligand present within the coordination sphere to form a new coordination complex.