Which of the following does not contain `PX_(4)^(+)` type cation in solid phase ?
(X=halogen atom)

Options

A. `PF_(5)`
B. `PCl_(5)`
C. `PBr_(5)`
D. None of these

Answer

To solve the question of which compound does not contain the `PX4^(+)` type cation in the solid phase, we need to analyze the behavior of phosphorus halides, particularly `PCl5`, `PBr5`, and `PF5`.

### Step 1: Understand the structure of phosphorus halides
Phosphorus halides can be represented as `PX5`, where `X` is a halogen atom. When these compounds are ionized, they can break down into cations and anions. The general reaction can be represented as:
\[ PX_5 \rightleftharpoons PX_4^+ + PX_6^- \]

### Step 2: Analyze the stability of the cations
The stability of the resulting `PX4^+` cation depends on the size of the halogen:
- Fluorine (F) is the smallest halogen, followed by Chlorine (Cl), Bromine (Br), and Iodine (I), which is the largest.
- As the size of the halogen increases, the stability of the `PX4^+` cation decreases due to increased steric hindrance and less effective overlap of orbitals.

### Step 3: Examine individual phosphorus halides
1. **PCl5**: When ionized, it can form `PCl4^+` and `PCl6^-`. Therefore, it contains `PCl4^+`.
2. **PBr5**: Similarly, it can decompose to form `PBr4^+` and `PBr6^-`, thus it contains `PBr4^+`.
3. **PF5**: In contrast, due to the small size of the fluoride ion, `PF5` does not decompose into `PF4^+` and `PF6^-`. It remains stable as `PF5` in the solid phase.

### Conclusion
Thus, the compound that does not contain the `PX4^+` type cation in solid phase is **PF5**.

### Final Answer
**PF5 does not contain `PX4^+` type cation in solid phase.**

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