Geometrical Isomerism
- Happens when ligands are arranged differently in space around the metal.
- Types:
- Cis → ligands next to each other.
- Trans → ligands opposite each other.
- Example: [Pt(NH₃)₂Cl₂] → cisplatin (drug) vs. transplatin (inactive).
- Not mirror images.
- Properties like color, solubility, and activity can change.
Optical Isomerism
- Happens when a complex is chiral (like left and right hands).
- Two forms = mirror images (enantiomers).
- They rotate plane-polarized light in opposite directions.
- Example: [Co(en)₃]³⁺ → has left-handed (Λ) and right-handed (Δ) forms.
- Same properties, except how they interact with light and living systems.
Difference in one line:
- Geometrical isomers = different positions (cis/trans).
- Optical isomers = mirror-image forms (chiral, rotate light).