`H_(3)C-overset(o+)CH-CH=CH_(2)` does not involve :

Options

A. `sigma-p` overlap
B. `sigma-pi^(**)` overlap
C. `ppi-ppi` overlap
D. `ppi-dpi` overlap

Answer

To solve the question regarding the carbocation \( \text{H}_3\text{C}^+\text{CH}=\text{CH}_2 \) and the types of overlaps it can involve, we will analyze the electronic configurations of the involved atoms and the types of overlaps mentioned.

### Step 1: Identify the structure of the carbocation
The given structure is \( \text{H}_3\text{C}^+\text{CH}=\text{CH}_2 \). This indicates that we have a carbocation at the first carbon atom, which is bonded to another carbon that has a double bond with a terminal carbon.

### Step 2: Determine the electronic configuration of involved atoms
- **Hydrogen (H)** has an electronic configuration of \( 1s^1 \).
- **Carbon (C)** has an electronic configuration of \( 1s^2 2s^2 2p_x^1 2p_y^1 \).

### Step 3: Analyze the types of overlaps
1. **Sigma (σ) overlap**: This occurs when orbitals overlap head-on. In our case, the overlap between \( \text{C-H} \) and \( \text{C-C} \) bonds is sigma overlap.
2. **Pi (π) overlap**: This occurs in the double bond between the second and third carbon atoms. The \( p \) orbitals of these carbons overlap sideways to form a π bond.
3. **Sigma star (σ*) overlap**: This is the antibonding counterpart of sigma bonds. It can occur in excited states or when considering molecular orbitals, but it is less relevant here.
4. **p π p π overlap**: This occurs in the double bond between the second and third carbon atoms, as both are involved in π bonding.
5. **p π d π overlap**: This type of overlap requires the involvement of d orbitals. However, neither hydrogen nor carbon has d orbitals in their electronic configuration.

### Step 4: Conclusion
Since both hydrogen and carbon lack d orbitals, they cannot form a p π d π overlap. Therefore, the answer to the question is that the carbocation \( \text{H}_3\text{C}^+\text{CH}=\text{CH}_2 \) does not involve **p π d π overlap**.

### Final Answer
The correct option is **p π d π overlap**.

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