Boron hydrides are chemical compounds made of boron (B) and hydrogen (H) only. They are also called boranes.
Here’s a clear breakdown:
1. Structure and Types
- Boron hydrides do not follow the usual rules of bonding (like octet rule).
- They often have cage-like or cluster structures.
- Common types:
- B₂H₆ (diborane) – simplest boron hydride
- B₄H₁₀, B₅H₉, B₆H₁₀ – larger clusters
- Bonding in boranes involves three-center two-electron (3c–2e) bonds, where two electrons are shared between three atoms.
2. Properties
- Highly reactive, especially with oxygen and water.
- Flammable and can release a lot of energy.
- Electron-deficient compounds – boron has fewer electrons than needed for normal bonding, which leads to unusual structures.
3. Importance / Applications
- Reducing agents
- Boron hydrides can donate hydrogen atoms in chemical reactions.
- Example: NaBH₄ (sodium borohydride) is widely used in reducing aldehydes and ketones in organic chemistry.
- Rocket fuels
- Some boron hydrides release a large amount of energy on combustion.
- Organic synthesis
- Hydroboration reaction: adds boron and hydrogen across double bonds in alkenes → useful in making alcohols.
- Materials chemistry
- Boron hydrides are precursors to boron-containing ceramics and polymers.
- Medicinal chemistry
- Some boron compounds are used in boron neutron capture therapy (BNCT) for cancer treatment.
In short:
Boron hydrides are electron-deficient, hydrogen-rich compounds of boron, important as reducing agents, reagents in organic synthesis, energy sources, and precursors for advanced materials.