Which of the following are bidentate monoanion ligands ?
(1) Acetylacetonato
(2)Oxalato ion
(3) Dimethylglyoxiamato
Select the correct answer using the codes given below :

Options

A. 1 only
B. 1 and 3 only
C. 3 only
D. 2 and 3 only

Explanation

To determine which of the given ligands are bidentate monoanionic ligands, we will analyze each ligand one by one.

### Step 1: Analyze Acetylacetonato
1. **Structure**: The acetylacetonato ion (often represented as acac) has the structure where it has two carbonyl (C=O) groups and two oxygen atoms that can donate electrons.
2. **Binding Sites**: The two oxygen atoms can coordinate to a metal center, making it a bidentate ligand.
3. **Charge**: Acetylacetonato has a single negative charge (−1), which qualifies it as a monoanionic ligand.

**Conclusion**: Acetylacetonato is a bidentate monoanionic ligand.

### Step 2: Analyze Oxalato Ion
1. **Structure**: The oxalato ion (C2O4^2−) has a structure with two carboxylate groups.
2. **Binding Sites**: It can bind through the two oxygen atoms, making it a bidentate ligand.
3. **Charge**: However, the oxalato ion carries a charge of −2, which means it is not monoanionic.

**Conclusion**: Oxalato ion is a bidentate ligand but not a monoanionic ligand.

### Step 3: Analyze Dimethylglyoxiamato
1. **Structure**: Dimethylglyoxiamato has a nitrogen atom and two carbonyl groups, with one of the oxygen atoms carrying a negative charge.
2. **Binding Sites**: It can bind through the nitrogen and one of the oxygen atoms, making it a bidentate ligand.
3. **Charge**: It has one negative charge (−1), qualifying it as a monoanionic ligand.

**Conclusion**: Dimethylglyoxiamato is a bidentate monoanionic ligand.

### Final Conclusion
Based on the analysis:
- Acetylacetonato: Bidentate monoanionic
- Oxalato ion: Bidentate but not monoanionic
- Dimethylglyoxiamato: Bidentate monoanionic

Thus, the correct answer is that the bidentate monoanionic ligands are **Acetylacetonato and Dimethylglyoxiamato**.

### Answer:
The correct choice is **(1) and (3) only**.

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