Diborane reacts with ammonia under different conditions to give a variety of products. Which one among the following is not formed in these reactions?

Options

A. `B_2 H_6 .2 NH_3`
B. `B_(12) H_(12)`
C. `B_3 N_3 H_6`
D. `(BN)_n`

Answer

To determine which product is not formed when diborane (B2H6) reacts with ammonia (NH3) under different conditions, we need to analyze the possible reactions and products formed during these interactions.

### Step-by-Step Solution:

1. **Identify the Reactants**: The primary reactants in this scenario are diborane (B2H6) and ammonia (NH3).

2. **Reactions at Low Temperature**:
- When diborane reacts with ammonia at low temperatures, it forms an addition product:
\[ B_2H_6 + 2 NH_3 \rightarrow BH_2NH_3^+ + BH_4^- \]
- This reaction results in the formation of a complex ion involving boron and ammonia.

3. **Reactions at High Temperature**:
- When diborane reacts with ammonia at high temperatures, it can lead to the formation of borazine:
\[ B_2H_6 + 3 NH_3 \rightarrow B_3N_3H_6 + 3 H_2 \]
- Borazine (B3N3H6) is a cyclic compound that resembles benzene and contains alternating boron and nitrogen atoms.

4. **Excess Ammonia at High Temperature**:
- If diborane reacts with excess ammonia at high temperatures, it can produce boron nitride (BN):
\[ B_2H_6 + 6 NH_3 \rightarrow BN + by-products \]
- Boron nitride is an inorganic compound that has properties similar to graphite.

5. **Identify the Incorrect Product**:
- The question asks which product is **not** formed in these reactions. The products we have identified are:
- BH2NH3^+ (from low temperature reaction)
- B3N3H6 (from high temperature reaction)
- BN (from excess ammonia at high temperature)
- The product B12H12, which is dodecaborane, is not formed in any of these reactions with ammonia.

### Conclusion:
The product that is not formed when diborane reacts with ammonia under different conditions is **B12H12**.

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