Which of the following has `ppi-dpi` bonding?

Options

A. `NO_(3) ^(-)`
B. `CO_(3) ^(-2)`
C. `BO_(3) ^(-3)`
D. `SO_(3) ^(-2)`

Answer

To determine which of the given compounds has p-pi d-pi bonding, we will analyze each option step by step.

### Step 1: Understand p-pi d-pi bonding
- **Definition**: p-pi d-pi bonding occurs when there is a sidewise overlap between a p orbital of one atom and a d orbital of another atom. This typically requires the presence of d orbitals in one of the bonding atoms.

### Step 2: Analyze each compound
1. **NO3⁻ (Nitrate ion)**:
- **Elements**: Nitrogen (N) and Oxygen (O).
- **Period**: Both N and O are in the second period.
- **D Orbitals**: No d orbitals are present in the second period.
- **Conclusion**: No p-pi d-pi bonding.

2. **CO3²⁻ (Carbonate ion)**:
- **Elements**: Carbon (C) and Oxygen (O).
- **Period**: Both C and O are in the second period.
- **D Orbitals**: No d orbitals are present in the second period.
- **Conclusion**: No p-pi d-pi bonding.

3. **BO3³⁻ (Boron trioxide)**:
- **Elements**: Boron (B) and Oxygen (O).
- **Period**: Both B and O are in the second period.
- **D Orbitals**: No d orbitals are present in the second period.
- **Conclusion**: No p-pi d-pi bonding.

4. **SO3²⁻ (Sulfite ion)**:
- **Elements**: Sulfur (S) and Oxygen (O).
- **Period**: Sulfur is in the third period, while O is in the second.
- **D Orbitals**: Sulfur has d orbitals available in its valence shell.
- **Conclusion**: p-pi d-pi bonding is possible.

### Step 3: Confirm bonding in SO3²⁻
- **Electronic Configuration of Sulfur**:
- 1s² 2s² 2p⁶ 3s² 3p⁴
- **Valence Electrons**: Sulfur has 6 valence electrons (3s² 3p⁴).
- **Excited State**: One electron from the 3p orbital can be promoted to an empty 3d orbital, allowing sulfur to have 4 unpaired electrons.
- **Bond Formation**:
- Sulfur can form three sigma bonds with oxygen and one pi bond.
- The pi bond is formed between the p orbital of oxygen and the d orbital of sulfur, confirming the presence of p-pi d-pi bonding.

### Final Answer
- The compound that exhibits p-pi d-pi bonding is **SO3²⁻**.

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