Which of the following compounds will exhibit d-orbital resonance?

Options

A.
B.
C.
D.

Explanation

To determine which of the given compounds will exhibit d-orbital resonance, we need to analyze the electronic structure of the elements involved, particularly focusing on phosphorus and chlorine, as they are the key players in this phenomenon.

### Step-by-Step Solution:

1. **Understanding d-Orbital Resonance**:
- d-orbital resonance occurs when a compound has a central atom with vacant d-orbitals that can accept electron density from neighboring atoms or groups. This typically involves elements from the third period and below in the periodic table, such as phosphorus and chlorine.

2. **Identifying the Elements**:
- We need to focus on phosphorus (P) and chlorine (Cl) as they are the elements that can exhibit d-orbital resonance. Carbon (C) does not have d-orbitals and thus cannot participate in d-orbital resonance.

3. **Evaluating Chlorine**:
- Chlorine is an electron-rich species with several lone pairs of electrons. While it has vacant d-orbitals, the presence of these lone pairs makes it less likely to participate in resonance with other electron-rich species. Therefore, chlorine is not a good candidate for d-orbital resonance.

4. **Evaluating Phosphorus**:
- Phosphorus, on the other hand, can be an electron-deficient species, especially when it carries a positive charge. It has vacant d-orbitals that can accept electrons. This makes phosphorus a suitable candidate for d-orbital resonance, as it can effectively participate in resonance with electron-donating groups.

5. **Conclusion**:
- Based on the analysis, phosphorus can participate in d-orbital resonance due to its electron deficiency and vacant d-orbitals, while chlorine cannot effectively participate due to its electron-rich nature. Therefore, the compound containing phosphorus will exhibit d-orbital resonance.

### Final Answer:
The compound that will exhibit d-orbital resonance is the one containing phosphorus.