Diborane is an electron-deficient compound.

Answer

**Step-by-Step Solution:**

1. **Understanding Diborane Structure**:
- The chemical formula of diborane is \( B_2H_6 \).
- It consists of two boron (B) atoms and six hydrogen (H) atoms.

2. **Boron’s Electron Requirement**:
- Boron is in group 13 of the periodic table and has three valence electrons.
- To achieve a stable electronic configuration, boron typically requires a total of 6 electrons to complete its octet (though it can be stable with fewer electrons).

3. **Bonding in Diborane**:
- In diborane, each boron atom forms bonds with two terminal hydrogen atoms.
- Additionally, the two boron atoms are connected by two bridging hydrogen atoms.

4. **Counting Electrons**:
- Each boron atom is bonded to 2 hydrogen atoms (2 electrons from each bond) and shares 2 electrons with the other boron atom through the bridging hydrogen atoms.
- Therefore, each boron atom effectively has access to only 4 electrons (2 from terminal H and 2 from bridging H).

5. **Conclusion**:
- Since each boron atom has only 4 electrons instead of the required 6 to complete its octet, diborane is classified as an electron-deficient compound.

**Final Statement**:
Thus, diborane \( B_2H_6 \) is an electron-deficient compound because each boron atom does not achieve a complete octet.

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