Question

Which type of isomerism is exhibited by the following complex ? \[ [Pt(NH_3)_2Cl_2] \]

Hint:

Square planar complexes of the type \[ [MA_2B_2] \] generally exhibit \[ \boxed{\text{Geometrical (cis-trans) isomerism}} \] Example: \[ [Pt(NH_3)_2Cl_2] \] exists as cis-platin and trans-platin.

Answer 1

Step 1: Identify the geometry of the complex.
Platinum(II) complexes are square planar. In $[Pt(NH_3)_2Cl_2]$, the central $Pt^{2+}$ is surrounded by two $NH_3$ and two $Cl^-$ ligands at the four corners of a square.
Step 2: Two possible spatial arrangements exist.
The two $Cl^-$ ligands can be placed at adjacent corners (cis form) or at diagonally opposite corners (trans form). Both have the same molecular formula but different three-dimensional structures.
Step 3: Name the type of isomerism.
Since the compounds differ only in the spatial arrangement of ligands (not in connectivity or bonding), this is geometrical isomerism (cis-trans isomerism). The cis isomer (cisplatin) is a well-known anticancer drug.