Borane

Borane

Examples of amine-borane complexes

Borane refers to a class of chemical compounds consisting of boron and hydrogen atoms. The simplest borane is diborane (B_H_), but the term "borane" is often used to refer to the entire class of boron-hydrogen compounds. Boranes are of significant interest in chemistry due to their unique bonding and structural properties.

Structure and Bonding

Boranes exhibit a variety of structures, often characterized by three-center two-electron (3c-2e) bonds. These bonds are a hallmark of borane chemistry, where two electrons are shared between three atoms, typically two boron atoms and one hydrogen atom. This type of bonding leads to the formation of clusters with various geometries, such as closo-, nido-, and arachno- structures.

Types of Boranes

Boranes can be classified based on the number of boron atoms and their structural arrangement:

• Closo-boranes: These are closed polyhedral structures where all vertices are occupied by boron atoms. An example is B_H___.
• Nido-boranes: These have an open structure with one vertex missing. An example is B_H_.
• Arachno-boranes: These have more open structures with two or more missing vertices. An example is B_H__.

Synthesis

Boranes are typically synthesized through the reaction of boron trihalides with reducing agents. For example, diborane can be prepared by the reduction of boron trifluoride with sodium hydride:

<math>2 BF_ + 6 NaH _ B_H_ + 6 NaF</math>

Applications

Boranes have several applications in chemistry and industry:

• Hydrogen storage: Due to their high hydrogen content, boranes are studied as potential hydrogen storage materials.
• Catalysis: Boranes are used as catalysts in various organic reactions, including hydroboration.
• Rocket propellants: Some boranes have been investigated as high-energy fuels for rocket propulsion.

Amine-Borane Complexes

Amine-borane complexes are a significant subclass of boranes, where an amine group is coordinated to a borane. These complexes are of interest due to their stability and potential applications in hydrogen storage. The image on the right shows examples of such complexes, illustrating the diversity of structures that can be formed.

Related Pages

• Diborane
• Borohydride
• Hydroboration
• Boron