In which of the following there is maximum `p pi -p pi` bonding ?

Options

A. `NF_(3)`
B. `NI_(3)`
C. `BI_(3)`
D. `BF_(3)`

Explanation

To determine which of the given compounds has the maximum `p pi - p pi` bonding, we need to analyze the electronic configurations and bonding capabilities of each compound. Let's go through the compounds one by one.

### Step-by-Step Solution:

1. **Understanding `p pi - p pi` Bonding:**
- `p pi - p pi` bonding occurs when there is a donation of electron density from a filled p orbital (donor) to an empty p orbital (acceptor). For effective bonding, the orbitals involved should have comparable energy levels.

2. **Analyzing NF3 (Nitrogen Trifluoride):**
- Nitrogen has the electronic configuration of 2s² 2p³.
- Fluorine has the configuration of 2s² 2p⁵.
- In NF3, nitrogen forms three bonds with fluorine, but there are no empty p orbitals in nitrogen to accept electron density from fluorine. Thus, `p pi - p pi` bonding is not possible here.

3. **Analyzing NI3 (Nitrogen Triiodide):**
- Iodine has the electronic configuration of 5s² 5p⁵.
- Similar to NF3, nitrogen forms three bonds with iodine. However, there are no empty p orbitals in nitrogen to accept electron density from iodine. Therefore, `p pi - p pi` bonding is not possible.

4. **Analyzing Bi3 (Boron Trifluoride):**
- Boron has the electronic configuration of 2s² 2p¹.
- Iodine has the configuration of 5s² 5p⁵.
- The energy difference between boron’s p orbitals and iodine’s p orbitals is significant, which makes effective overlapping and `p pi - p pi` bonding unlikely.

5. **Analyzing BF3 (Boron Trifluoride):**
- Boron has the electronic configuration of 2s² 2p¹.
- Fluorine has the configuration of 2s² 2p⁵.
- In BF3, boron can form three bonds with fluorine, and the empty p orbital of boron can accept electron density from the filled p orbital of fluorine. The energy levels of the involved orbitals are comparable, allowing for effective `p pi - p pi` bonding.

### Conclusion:
Among the compounds analyzed, **BF3 (Boron Trifluoride)** exhibits the maximum `p pi - p pi` bonding due to the effective overlap of the p orbitals of boron and fluorine.

### Final Answer:
**The compound with maximum `p pi - p pi` bonding is BF3.**