Question

Discuss the important applications of coordination compounds.

Answer 1

Coordination compounds play a vital role in various fields such as medicine, industry, biology, and analytical chemistry. Their unique chemical properties like variable oxidation states, colour, magnetism, and stability make them extremely useful.

1. Analytical Chemistry:

1. Detection of metal ions: Complexes like [Fe(SCN)]²⁺ are used in colorimetric tests to detect iron.
2. Complexometric titrations: EDTA is widely used in the quantitative estimation of metal ions such as Ca²⁺ and Mg²⁺.

2. The estimation of hardness of water:

1. The hardness of water is caused by the presence of Ca²⁺ and Mg²⁺ ions.
2. The hexadentate ligand EDTA (ethylenediaminetetraacetato) forms stable complexes with Ca²⁺ and Mg²⁺ ions and can be used to determine the hardness of water using a simple titration approach.

3. Extraction and Purification of Metals: Coordination compounds are used in processes like:

1. The cyanide process is used for extracting gold and silver.
2. Froth flotation using metal collectors that form complexes with the metal ores.

4. Electroplating:

1. The complexes are relatively stable and dissolve in solution to a minimal extent, they provide a regulated supply of metal ions.
2. This feature of complexes has been employed for electroplating noble metals such as silver and gold.

5. Medicinal Applications:

1. Cisplatin [Pt(NH₃​)₂​Cl₂​]: A coordination compound used as an anti-cancer drug in chemotherapy.
2. Chelation therapy: Compounds like EDTA are used to remove toxic metal ions (like lead or mercury) from the body by forming stable complexes.

6. Modifying the redox behaviour of metai ions:

1. The redox behaviour of a metal ion can be altered by complexing it with a specific type of ligand.
2. Cobalt, for example, can easily be oxidized from +2 to +3 in the presence of certain ligands.

7. Biological Importance:

1. Hemoglobin: A coordination compound of iron that transports oxygen in the blood.
2. Chlorophyll: A coordination compound of magnesium involved in photosynthesis.
3. Vitamin B₁₂: Contains cobalt in a coordination complex; essential for DNA synthesis and nerve function.