`d_pi - p_pi` bonding exists in

Options

A. diamond
B. graphite
C. trisilylamine
D. none of these

Explanation

To determine where d_pi - p_pi bonding exists among the options given (diamond, graphite, trisilyl amine, or none of these), we can analyze each option step by step.

### Step 1: Understanding d_pi - p_pi Bonding
d_pi - p_pi bonding occurs when there is interaction between d orbitals of one atom and p orbitals of another atom. This type of bonding is typically seen in transition metal complexes where d orbitals are available for bonding.

### Step 2: Analyzing Diamond
- Diamond is a form of carbon where each carbon atom is tetrahedrally coordinated to four other carbon atoms.
- The bonding in diamond involves only sp^3 hybridization, which means it utilizes s and p orbitals.
- There are no d orbitals involved in the bonding in diamond.

**Conclusion for Diamond**: No d_pi - p_pi bonding exists in diamond.

### Step 3: Analyzing Graphite
- Graphite is another form of carbon, where each carbon atom is bonded to three other carbon atoms in a planar hexagonal arrangement.
- The bonding in graphite involves sp^2 hybridization, which again does not involve d orbitals.
- Therefore, there is no d_pi - p_pi bonding in graphite.

**Conclusion for Graphite**: No d_pi - p_pi bonding exists in graphite.

### Step 4: Analyzing Trisilyl Amine
- Trisilyl amine consists of a nitrogen atom bonded to three silicon atoms.
- In this structure, nitrogen has a lone pair of electrons that can interact with the d orbitals of silicon.
- Silicon has available d orbitals (since it is in the third period of the periodic table), allowing for the formation of d_pi - p_pi bonding with the nitrogen's p orbital.

**Conclusion for Trisilyl Amine**: Yes, d_pi - p_pi bonding exists in trisilyl amine.

### Final Answer
Based on the analysis, the correct answer is **trisilyl amine**.

---