key term - Diborane

Definition

Diborane is a chemical compound with the formula B₂H₆, consisting of two boron atoms and six hydrogen atoms. It is a colorless gas at room temperature and exhibits unique bonding characteristics, including the presence of three-center two-electron bonds, which are critical in understanding the reactivity and structure of boron compounds.

5 Must Know Facts For Your Next Test

1. Diborane is synthesized by reacting boron trifluoride with lithium aluminum hydride, illustrating its role as a key compound in boron chemistry.
2. The unique three-center two-electron bond structure in diborane allows for significant stability and reactivity, setting it apart from typical covalent compounds.
3. Diborane can act as a Lewis acid, which makes it highly reactive with electron-rich species, contributing to its use in organic reactions.
4. Due to its low boiling point of -92 °C, diborane is often stored under pressure as a gas or as a stabilized solution.
5. Diborane undergoes hydrolysis in the presence of water to produce boric acid and hydrogen gas, showcasing its reactivity with moisture.

Review Questions

• How does the structure of diborane contribute to its unique chemical properties compared to typical covalent compounds?
  • Diborane features a distinctive structure that includes three-center two-electron bonds, where two boron atoms share electrons with adjacent hydrogen atoms. This bonding arrangement allows for greater stability and reactivity than typical two-center two-electron bonds found in conventional covalent compounds. The ability of diborane to form these bonds enables it to participate in various chemical reactions and interact effectively with other molecules.
• Discuss how diborane can function as a Lewis acid and the implications this has for its reactivity in chemical reactions.
  • As a Lewis acid, diborane can accept electron pairs from nucleophiles, allowing it to react readily with electron-rich species. This property enhances its versatility as a reagent in organic synthesis, where it can facilitate hydroboration reactions with alkenes. The ability to form stable adducts with various substrates showcases its significance in both inorganic and organic chemistry.
• Evaluate the importance of diborane in synthetic chemistry, particularly focusing on its role in hydroboration and the formation of organoboranes.
  • Diborane is crucial in synthetic chemistry due to its role in hydroboration reactions, which involve the addition of diborane to alkenes to create organoboranes. These organoboranes serve as valuable intermediates for further transformations, such as oxidation to alcohols or coupling reactions. By enabling these transformations, diborane plays a pivotal role in organic synthesis, enhancing the efficiency and variety of synthetic pathways available to chemists.

Related terms

boranes:

A class of chemical compounds that include boron and hydrogen, characterized by various structures and bonding patterns, with diborane being one of the simplest members.

Lewis Acid: A substance that can accept an electron pair from a donor in a chemical reaction, often utilized to describe the behavior of boron compounds, including diborane.

hydroboration: A chemical reaction that involves the addition of diborane to alkenes to form organoboranes, which are useful intermediates in organic synthesis.