Which of the following elements can be involved in `ppi-dpi` bonding?

Options

A. Carbon
B. Nitrogen
C. phosphorus
D. Boron

Explanation

To determine which of the given elements can be involved in pπ-dπ bonding, we need to analyze the electronic configurations of each element and check for the presence of d orbitals in their valence shells.

### Step-by-Step Solution:

1. **Understanding pπ-dπ Bonding**:
- pπ-dπ bonding occurs when there is a formation of a pi bond involving p orbitals from one atom and d orbitals from another atom. For this to happen, at least one of the atoms must have d orbitals available in its valence shell.

2. **Analyzing Carbon**:
- Electronic Configuration: Carbon (C) = 1s² 2s² 2p²
- Valence Shell: The valence shell is the second shell (n=2), which contains only s and p orbitals. There are no d orbitals in the second shell.
- Conclusion: Carbon cannot participate in pπ-dπ bonding.

3. **Analyzing Nitrogen**:
- Electronic Configuration: Nitrogen (N) = 1s² 2s² 2p³
- Valence Shell: Similar to carbon, nitrogen's valence shell is also the second shell (n=2) and contains only s and p orbitals.
- Conclusion: Nitrogen cannot participate in pπ-dπ bonding.

4. **Analyzing Phosphorus**:
- Electronic Configuration: Phosphorus (P) = 1s² 2s² 2p⁶ 3s² 3p³
- Valence Shell: The valence shell is the third shell (n=3), which includes s, p, and d orbitals. The 3d orbitals are available and can be vacant.
- Conclusion: Phosphorus can participate in pπ-dπ bonding due to the presence of vacant d orbitals.

5. **Analyzing Boron**:
- Electronic Configuration: Boron (B) = 1s² 2s² 2p¹
- Valence Shell: Boron's valence shell is the second shell (n=2), which does not contain any d orbitals.
- Conclusion: Boron cannot participate in pπ-dπ bonding.

### Final Answer:
The only element that can be involved in pπ-dπ bonding is **Phosphorus (P)**.