Decaborane, also called decaborane(14), is the

inorganic compound An inorganic compound is typically a chemical compound that lacks carbon–hydrogen bonds⁠that is, a compound that is not an organic compound. The study of inorganic compounds is a subfield of chemistry known as ''inorganic chemistry''. Inorgan ...

with the

chemical formula A chemical formula is a way of presenting information about the chemical proportions of atoms that constitute a particular chemical compound or molecule, using chemical element symbols, numbers, and sometimes also other symbols, such as pare ...

B₁₀ H₁₄. It is classified as a borane and more specifically a boron hydride cluster. This white crystalline compound is one of the principal boron hydride clusters, both as a reference structure and as a precursor to other boron hydrides. It is toxic and volatile, giving off a foul odor, like that of burnt rubber or chocolate.

Handling, properties and structure

The physical characteristics of decaborane(14) resemble those of

naphthalene Naphthalene is an organic compound with formula . It is the simplest polycyclic aromatic hydrocarbon, and is a white Crystal, crystalline solid with a characteristic odor that is detectable at concentrations as low as 0.08 Parts-per notation ...

and anthracene, all three of which are volatile colorless solids. Sublimation is the common method of purification. Decaborane is highly flammable, and burns with a bright green flame like other boron hydrides. It is not sensitive to moist air, although it hydrolyzes in boiling water, releasing hydrogen and giving a solution of

boric acid Boric acid, more specifically orthoboric acid, is a compound of boron, oxygen, and hydrogen with formula . It may also be called hydrogen orthoborate, trihydroxidoboron or boracic acid. It is usually encountered as colorless crystals or a white ...

. It is soluble in cold water as well as a variety of non-polar and moderately polar

solvent A solvent (from the Latin language, Latin ''wikt:solvo#Latin, solvō'', "loosen, untie, solve") is a substance that dissolves a solute, resulting in a Solution (chemistry), solution. A solvent is usually a liquid but can also be a solid, a gas ...

s. In decaborane, the B₁₀ framework resembles an incomplete

octadecahedron In geometry, an octadecahedron (or octakaidecahedron) is a polyhedron with 18 face (geometry), faces. No octadecahedron is regular polyhedron, regular; hence, the name does not commonly refer to one specific polyhedron. In chemistry, "''the'' oc ...

. Each boron atom has one "radial" hydride, and four boron atoms near the open part of the cluster feature extra bridging hydrides. In the language of cluster chemistry, the structure is classified as "nido".

Synthesis and reactions

It is commonly synthesized via the

pyrolysis Pyrolysis is a process involving the Bond cleavage, separation of covalent bonds in organic matter by thermal decomposition within an Chemically inert, inert environment without oxygen. Etymology The word ''pyrolysis'' is coined from the Gree ...

of smaller boron hydride clusters. For example, pyrolysis of B₂H₆ or B₅H₉ gives decaborane, with loss of H₂. On a laboratory scale, sodium borohydride is treated with boron trifluoride to give NaB₁₁H₁₄, which is acidified to release borane and hydrogen gas.Gary B. Dunks, Kathy Palmer-Ordonez, Eddie Hedaya "Decaborane(14)" Inorg. Synth. 1983, vol. 22, pp. 202–207. It reacts with Lewis bases (L) such as CH₃CN and Et₂S, to form adducts: :B₁₀H₁₄ + 2 L → B₁₀H₁₂L₂ + H₂ These species, which are classified as "arachno" clusters, in turn react with

acetylene Acetylene (Chemical nomenclature, systematic name: ethyne) is a chemical compound with the formula and structure . It is a hydrocarbon and the simplest alkyne. This colorless gas is widely used as a fuel and a chemical building block. It is u ...

to give the "closo" ortho-carborane: :B₁₀H₁₂·2L + C₂H₂ → C₂B₁₀H₁₂ + 2 L + H₂ Decaborane(14) is a weak Brønsted acid. Monodeprotonation generates the

anion An ion () is an atom or molecule with a net electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by conven ...

₁₀H₁₃sup>−, with again a nido structure. In the Brellochs reaction, decaborane is converted to arachno-CB₉H₁₄⁻: :B₁₀H₁₄ + CH₂O + 2 OH⁻ + H₂O → CB₉H₁₄⁻ + B(OH)₄⁻ + H₂

Possible applications

Decaborane has no significant commercial applications, although the compound has often been investigated. It and its derivatives were investigated as an additive to special high-performance rocket fuels. Its derivates were investigated as well, e.g. ethyl decaborane. Decaborane is an effective reagent for the reductive amination of ketones and aldehydes. Decaborane has been assessed for low energy

ion implantation Ion implantation is a low-temperature process by which ions of one element are accelerated into a solid target, thereby changing the target's physical, chemical, or electrical properties. Ion implantation is used in semiconductor device fabrica ...

of boron in the manufacture of

semiconductor A semiconductor is a material with electrical conductivity between that of a conductor and an insulator. Its conductivity can be modified by adding impurities (" doping") to its crystal structure. When two regions with different doping level ...

s. It has also been considered for plasma-assisted

chemical vapor deposition Chemical vapor deposition (CVD) is a vacuum deposition method used to produce high-quality, and high-performance, solid materials. The process is often used in the semiconductor industry to produce thin films. In typical CVD, the wafer (electro ...

for the manufacture of boron-containing

thin film A thin film is a layer of materials ranging from fractions of a nanometer ( monolayer) to several micrometers in thickness. The controlled synthesis of materials as thin films (a process referred to as deposition) is a fundamental step in many ...

s. In fusion research, the

neutron The neutron is a subatomic particle, symbol or , that has no electric charge, and a mass slightly greater than that of a proton. The Discovery of the neutron, neutron was discovered by James Chadwick in 1932, leading to the discovery of nucle ...

-absorbing nature of boron has led to the use of these thin boron-rich films to "boronize" the walls of the

tokamak A tokamak (; ) is a device which uses a powerful magnetic field generated by external magnets to confine plasma (physics), plasma in the shape of an axially symmetrical torus. The tokamak is one of several types of magnetic confinement fusi ...

vacuum vessel to reduce recycling of particles and impurities into the plasma and improve overall performance. It has been evaluated in the context of

nuclear fusion Nuclear fusion is a nuclear reaction, reaction in which two or more atomic nuclei combine to form a larger nuclei, nuclei/neutrons, neutron by-products. The difference in mass between the reactants and products is manifested as either the rele ...

Safety

Decaborane, like pentaborane, is a powerful toxin affecting the

central nervous system The central nervous system (CNS) is the part of the nervous system consisting primarily of the brain, spinal cord and retina. The CNS is so named because the brain integrates the received information and coordinates and influences the activity o ...

, although decaborane is less toxic than pentaborane. It can be absorbed through skin. Purification by sublimation require a dynamic vacuum to remove evolved gases. Crude samples explode near 100 °C. It forms an explosive mixture with

carbon tetrachloride Carbon tetrachloride, also known by many other names (such as carbon tet for short and tetrachloromethane, also IUPAC nomenclature of inorganic chemistry, recognised by the IUPAC), is a chemical compound with the chemical formula CCl4. It is a n ...

, which caused an often-mentioned explosion in a manufacturing facility. In crystalline form, it reacts violently with red and white fuming nitric acid which has a use as rocket fuel oxidizer, producing an extremely powerful detonation.

Handling, properties and structure

Synthesis and reactions

Possible applications

Safety

References

Further reading