Question

The denticity of an organic ligand, biuret is :

• A. 2
• B. 4
• C. 6
• D. 3

Hint:

A ligand with denticity 2 is called "bidentate". Chelating ligands like biuret or ethylenediamine form rings that are more stable than non-chelating complexes.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Denticity is the number of donor atoms in a ligand that bind to a central metal atom in a coordination complex.
Step 2: Detailed Explanation:
1. Structure: Biuret (\( \text{NH}_2\text{CONHCONH}_2 \)) is formed by the condensation of two molecules of urea.
2. Donor Sites: It contains several nitrogen and oxygen atoms. However, it typically acts as a bidentate ligand.
3. Coordination: In most complexes, it coordinates through its two oxygen atoms or nitrogen atoms to form a stable chelate ring with the metal.
4. Example: In the biuret test for proteins, biuret complexes with Copper (\( \text{II} \)) ions using two coordination sites.
Step 3: Final Answer:
The denticity of biuret is 2.