Which of the following ligands will not show chelation ?

Options

A. EDTA
B. DMG
C. Ethane-1, 2- diamine
D. `SCN^(-)`

Explanation

To determine which ligand will not show chelation, we need to understand the concept of chelation and the types of ligands involved in coordination chemistry.

### Step-by-Step Solution:

1. **Understand Chelation**:
- Chelation occurs when a ligand forms multiple bonds with a metal ion, resulting in a ring-like structure. This is important for the stability of the complex.

2. **Identify Ligands**:
- Ligands can be classified based on their denticity (the number of donor atoms that can bind to a central metal atom).
- Monodentate ligands have only one donor atom and can form only one bond with the metal ion.
- Bidentate ligands can form two bonds, and polydentate ligands can form multiple bonds.

3. **Determine Ligand Types**:
- In the given options, identify which ligands are monodentate and which are bidentate or polydentate.
- For example, thiocyanate (SCN⁻) is a monodentate ligand because it can only attach to the metal through one atom (the sulfur or nitrogen).

4. **Conclusion**:
- Since monodentate ligands cannot form ring structures with metal ions, they do not exhibit the chelation effect.
- Therefore, the ligand that will not show chelation is thiocyanate (SCN⁻).

### Final Answer:
The ligand that will not show chelation is **thiocyanate (SCN⁻)**.

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