The molecule in which an atom is associated with more than 8 electrons is known as hypervalent molecule and less than 8 electrons is known as hypovalent molecule. All hypervalent molecules must have `ppi-dpi` bonding but the molecules having back bonding back boding need not to have always `ppi-dpi` bondin.
Q.Which of the following molecule is not having `ppi-dpi` bonding:

Options

A. `SO_(2)`
B. `P_(4)O_(10)`
C. `PF_(3)`
D. `B_(3)N_(3)H_(6)`

Answer

To determine which of the given molecules does not have p-pi d-pi bonding, we will analyze each option step by step.

### Step 1: Analyze SO2
- **Valence Electrons**: Sulfur (S) has 6 valence electrons.
- **Structure**: In SO2, sulfur forms two sigma bonds with oxygen and has one lone pair.
- **Bonding**: The pi bonds involve:
- One p-pi p-pi overlap (between sulfur and oxygen).
- One p-pi d-pi overlap (between sulfur and oxygen).
- **Conclusion**: SO2 has p-pi d-pi bonding.

### Step 2: Analyze P4O10
- **Valence Electrons**: Phosphorus (P) has 5 valence electrons and there are 10 oxygen atoms.
- **Structure**: Each phosphorus atom forms 5 bonds (4 sigma and 1 pi).
- **Bonding**: The pi bond involves:
- p-pi d-pi overlap (between phosphorus and oxygen).
- **Conclusion**: P4O10 has p-pi d-pi bonding.

### Step 3: Analyze PF3
- **Valence Electrons**: Phosphorus has 5 valence electrons, and each fluorine has 7.
- **Structure**: In PF3, phosphorus forms three sigma bonds with fluorine.
- **Bonding**: The pi bond involves:
- p-pi d-pi overlap (between phosphorus and fluorine).
- **Conclusion**: PF3 has p-pi d-pi bonding.

### Step 4: Analyze B3N3H6 (Inorganic Benzene)
- **Valence Electrons**: Boron (B) has 3 valence electrons and nitrogen (N) has 5.
- **Structure**: The structure alternates between boron and nitrogen atoms, forming a cyclic compound.
- **Bonding**: The pi bonds are formed by:
- p-pi p-pi overlap (between boron and nitrogen).
- **Conclusion**: B3N3H6 does not have p-pi d-pi bonding, as boron and nitrogen do not have d-orbitals.

### Final Conclusion
The molecule that does not have p-pi d-pi bonding is **B3N3H6**.

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