Which of the following isomerism, exhibited by octahedral $\left[\mathrm{Co}{\left({\mathrm{NH}}_3\right)}_4{\mathrm{Br}}_2\right]\mathrm{Cl}l?$

$\left[\mathrm{Co}{\left({\mathrm{NH}}_3\right)}_4{\mathrm{Br}}_2\right]\mathbf{Cl}$ complex

• In $\left[\mathrm{Co}{\left({\mathrm{NH}}_3\right)}_4{\mathrm{Br}}_2\right]\mathrm{Cl}$, center metal cobalt is in a $+3$ oxidation state.
• $\left[\mathrm{Co}{\left({\mathrm{NH}}_3\right)}_4{\mathrm{Br}}_2\right]\mathrm{Cl}$ has ionization isomers.
• This isomerism occurs due to the interchange of ions between the inner and the outer coordination sphere.
• Ionization isomers can be written as:

$\left[\mathrm{Co}{\left({\mathrm{NH}}_3\right)}_4{\mathrm{Br}}_2\right]\mathrm{Cl}$ and $\left[\mathrm{Co}{\left({\mathrm{NH}}_3\right)}_4\mathrm{BrCl}\right]\mathrm{Br}$

• This isomerism comes as a result of ion exchange between the inner and outer coordination spheres.
• Although it can form geometric isomers, cis and trans, neither is optically active.
• Structure are as follows: