For any of the following that can exist as isomers, state the type of isomerism and draw the structures:

1. ^- $\left[\mathbf{PtCl}\mathbf{2}\mathbf{Br}\mathbf{2}\right]\mathbf{2}$
2. ^{-$\left[\mathbf{Cr}\left(\mathbf{NH}\mathbf{3}\right)\mathbf{5}\left(\mathbf{NO}\mathbf{2}\right)\right]\mathbf{2}$}
3. ^{-$\left[\mathbf{Pt}\left(\mathbf{NH}\mathbf{3}\right)\mathbf{4}\mathbf{I}\mathbf{2}\right]\mathbf{2}$}

Definition of different kinds of isomers

Constitutional (structural) isomers– They have same formula, but differently connected atoms; they can occur in two types:

Coordination isomers - They occur when the structure of the whole compound is the same, but the structure of complex ion is different

Linkage isomers - They occur when the structure of the complex ion is the same, but the donor atom to which ligand attached is different

Stereoisomers- They have the same connections between atoms, but the atoms have different spatial arrangements; they occur in two types:

geometric (cis-trans) isomers - different spatial arrangements of atoms or groups, relative to the central metal ion.

2.2 Optical isomers - They occur when a molecule cannot be superimposed with its mirror image.

${\left[\mathrm{PtCl}2\mathrm{Br}2\right]}^{2-}$- Geometric (cis-trans) Isomerism

${\left[\mathrm{Cr}\left(\mathrm{NH}3\right)5\left(\mathrm{NO}2\right)\right]}^{2-}$- Linkage Isomerism

${\left[\mathrm{Pt}\left(\mathrm{NH}3\right)4\mathrm{I}2\right]}^{2-}$- Geometric (cis-trans) Isomerism