Which of the following orbital can not form `pi` as well as `delta`-Bond ?

Options

A. `d_(xy)`
B. `d_(z^(2))`
C. `d_(x^(2)-y^(2))`
D. `d_(yz)`

Explanation

To determine which of the following orbitals cannot form a pi bond as well as a delta bond, we need to analyze the characteristics of the orbitals provided in the options.

### Step-by-step Solution:

1. **Understanding Pi Bonds:**
- Pi bonds are formed by the sidewise overlap of p orbitals. For example, when two p orbitals (like px and py) approach each other, they can overlap sideways to form a pi bond.

2. **Understanding Delta Bonds:**
- Delta bonds are formed by the overlap of d orbitals. Specifically, for a delta bond to form, all four lobes of two d orbitals must overlap perfectly. This typically occurs when two dxy orbitals align properly.

3. **Analyzing the Given Orbitals:**
- **Option A: dxy**
- The dxy orbital can form both pi and delta bonds due to its ability to overlap with another dxy orbital.
- **Option B: dz²**
- The dz² orbital has a unique shape with a ring structure around the z-axis. This configuration prevents it from forming pi bonds due to the lack of sidewise overlap. Additionally, the ring structure inhibits the necessary overlap for delta bonding as well.
- **Option C: dx²-y²**
- The dx²-y² orbital can form both pi and delta bonds. It can overlap with another dx²-y² orbital to form a delta bond.
- **Option D: dyz**
- The dyz orbital can also form both pi and delta bonds. It can overlap with another dyz orbital to form a delta bond and can overlap with p orbitals to form a pi bond.

4. **Conclusion:**
- After analyzing all the options, we find that the dz² orbital (Option B) cannot form either a pi bond or a delta bond due to its unique shape and the lack of proper overlapping capability.

### Final Answer:
**The orbital that cannot form a pi bond as well as a delta bond is: Option B (dz²).**