The reason for the formation of hydrogen bridge bond in `B_2 H_6` is

Options

A. that it has 14 electrons to form bonds
B. that it has shortage of electrons
C. to get structure similar to `C_2 H_6`
D. that the boron atoms have lone electron pairs

Answer

To understand the formation of hydrogen bridge bonds in diborane (B₂H₆), we can break down the explanation into a step-by-step solution.

### Step-by-Step Solution:

1. **Understanding the Structure of B₂H₆**:
- Diborane consists of two boron (B) atoms and six hydrogen (H) atoms. The molecular formula is B₂H₆.
- Each boron atom has three valence electrons, leading to a total of 6 electrons from boron. The six hydrogen atoms contribute 6 electrons, giving a total of 12 electrons.

2. **Electron Deficiency**:
- In B₂H₆, there are only 12 valence electrons available for bonding, which is insufficient for forming a stable structure similar to ethane (C₂H₆), which has 14 electrons.
- This deficiency means that B₂H₆ cannot form conventional two-electron bonds for all its hydrogen atoms.

3. **Hybridization**:
- The boron atoms in diborane undergo sp³ hybridization. Each boron atom forms four sp³ hybrid orbitals: three of these orbitals form bonds with hydrogen atoms, and one remains empty.
- This hybridization allows for the formation of a unique bonding arrangement.

4. **Formation of Hydrogen Bridge Bonds**:
- Due to the electron deficiency and the empty p-orbital on each boron atom, two hydrogen atoms act as bridges between the two boron atoms.
- These hydrogen atoms form what are known as "three-center two-electron bonds." In this arrangement, two boron atoms and one hydrogen atom share the same pair of electrons, effectively creating a bridge.

5. **Conclusion**:
- The formation of hydrogen bridge bonds in B₂H₆ is a result of its electron deficiency and the unique bonding capabilities of boron, which allows for the creation of these three-center two-electron bonds.