Decaborane
Encyclopedia
Decaborane, also called decaborane(14), is the borane
with the chemical formula
B
10H
14. 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.
s. The physical characteristics of decaborane(14) resemble those of the organic compounds, such as naphthalene
and anthracene
, in that it can be sublimed under vacuum at moderate temperatures. Sublimation
is the common method of purification. Like organic compounds, decaborane is highly flammable, but, like other boron hydrides, it burns with a bright green flame. It is not sensitive to moist air, although it hydrolyzes in boiling water, releasing hydrogen and giving a solution of boric acid
. It is soluble in cold water as well as a variety of non-polar and moderately polar solvent
s.
In decaborane, the B10 framework resembles an incomplete octadecahedron. Each boron has one "radial" hydride, and four boron atoms near the open part of the cluster feature extra hydrides. In the language of cluster chemistry, the structure is classified as "nido".
of smaller boron hydride clusters
. For example, heating B2H6
or B5H9
gives decaborane, with loss of H2.
It reacts with Lewis bases (L) such as CH3CN
and Me2S
, to form derivatives with the formula B10H12·2L.
These species, which are classified as "arachno" clusters, in turn react with acetylene
to give the "closo" ortho-carborane
:
It is a weak Brønsted acid. Monodeprotonation generates the anion [B10H13]−, with again a nido structure.
, and for low energy ion implantation
of boron in the manufacture of semiconductor
s. It has also been considered for plasma
-assisted chemical vapor deposition
for the manufacture boron-containing thin film
s. In fusion research, the neutron
-absorbing nature of boron has led to the use of these thin boron-rich films to "boronize" the walls of the tokamak
vacuum vessel to reduce recycling of particles and impurities into the plasma and improve overall performance.
Decaborane was also developed as an additive to special high-performance rocket fuels. Its derivates were investigated as well, e.g. ethyl decaborane. One patented fuel composition included vinyl decaborane-polyester
copolymer. Vinyl decaborane ("dekene") is prepared by reacting decaborane with acetylene
.
, is a powerful toxin affecting central nervous system
, although decaborane is less toxic than pentaborane. It can be absorbed through skin. It forms an explosive mixture with carbon tetrachloride
, which caused an often quoted explosion in a Malta, NY
manufacturing facility in 1948 when CCl4 was used to clean the equipment.
Borane
In chemistry, a borane is a chemical compound of boron and hydrogen. The boranes comprise a large group of compounds with the generic formulae of BxHy. These compounds do not occur in nature. Many of the boranes readily oxidise on contact with air, some violently. The parent member BH3 is called...
with the chemical formula
Chemical formula
A chemical formula or molecular formula is a way of expressing information about the atoms that constitute a particular chemical compound....
B
Boron
Boron is the chemical element with atomic number 5 and the chemical symbol B. Boron is a metalloid. Because boron is not produced by stellar nucleosynthesis, it is a low-abundance element in both the solar system and the Earth's crust. However, boron is concentrated on Earth by the...
10H
Hydrogen
Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...
14. 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.
Handling properties and structure
B10H14 possesses a strong characteristic odor, sometimes described as musty or intensely bitter, chocolate-like that is unique to boraneBorane
In chemistry, a borane is a chemical compound of boron and hydrogen. The boranes comprise a large group of compounds with the generic formulae of BxHy. These compounds do not occur in nature. Many of the boranes readily oxidise on contact with air, some violently. The parent member BH3 is called...
s. The physical characteristics of decaborane(14) resemble those of the organic compounds, such as naphthalene
Naphthalene
Naphthalene is an organic compound with formula . It is a white crystalline solid with a characteristic odor that is detectable at concentrations as low as 0.08 ppm by mass. As an aromatic hydrocarbon, naphthalene's structure consists of a fused pair of benzene rings...
and anthracene
Anthracene
Anthracene is a solid polycyclic aromatic hydrocarbon consisting of three fused benzene rings. It is a component of coal-tar. Anthracene is used in the production of the red dye alizarin and other dyes...
, in that it can be sublimed under vacuum at moderate temperatures. Sublimation
Sublimation (physics)
Sublimation is the process of transition of a substance from the solid phase to the gas phase without passing through an intermediate liquid phase...
is the common method of purification. Like organic compounds, decaborane is highly flammable, but, like other boron hydrides, it burns with a bright green flame. It is not sensitive to moist air, although it hydrolyzes in boiling water, releasing hydrogen and giving a solution of boric acid
Boric acid
Boric acid, also called hydrogen borate or boracic acid or orthoboric acid or acidum boricum, is a weak acid of boron often used as an antiseptic, insecticide, flame retardant, as a neutron absorber, and as a precursor of other chemical compounds. It exists in the form of colorless crystals or a...
. It is soluble in cold water as well as a variety of non-polar and moderately polar solvent
Solvent
A solvent is a liquid, solid, or gas that dissolves another solid, liquid, or gaseous solute, resulting in a solution that is soluble in a certain volume of solvent at a specified temperature...
s.
In decaborane, the B10 framework resembles an incomplete octadecahedron. Each boron has one "radial" hydride, and four boron atoms near the open part of the cluster feature extra hydrides. In the language of cluster chemistry, the structure is classified as "nido".
Synthesis and reactions
It is commonly synthesized via the pyrolysisPyrolysis
Pyrolysis is a thermochemical decomposition of organic material at elevated temperatures without the participation of oxygen. It involves the simultaneous change of chemical composition and physical phase, and is irreversible...
of smaller boron hydride clusters
Cluster (physics)
In physics, the term clusters denotes small, multiatom particles. As a rule of thumb, any particle of somewhere between 3 and 3x107 atoms is considered a cluster. Two-atom particles are sometimes considered clusters as well....
. For example, heating B2H6
Diborane
Diborane is the chemical compound consisting of boron and hydrogen with the formula B2H6. It is a colorless gas at room temperature with a repulsively sweet odor. Diborane mixes well with air, easily forming explosive mixtures. Diborane will ignite spontaneously in moist air at room temperature...
or B5H9
Pentaborane
Pentaborane, also called pentaborane to distinguish it from B5H11, is an inorganic compound with the formula B5H9. It is one of the most common boron hydride clusters, although it is a highly reactive compound. Because of its high reactivity toward oxygen, it was once evaluated as rocket or jet fuel...
gives decaborane, with loss of H2.
It reacts with Lewis bases (L) such as CH3CN
Acetonitrile
Acetonitrile is the chemical compound with formula . This colourless liquid is the simplest organic nitrile. It is produced mainly as a byproduct of acrylonitrile manufacture...
and Me2S
Dimethyl sulfide
Dimethyl sulfide or methylthiomethane is an organosulfur compound with the formula 2S. Dimethyl sulfide is a water-insoluble flammable liquid that boils at and has a characteristic disagreeable odor. It is a component of the smell produced from cooking of certain vegetables, notably maize,...
, to form derivatives with the formula B10H12·2L.
- B10H14 + 2 L → B10H12L2 + H2
These species, which are classified as "arachno" clusters, in turn react with acetylene
Acetylene
Acetylene is the chemical compound with the formula C2H2. It is a hydrocarbon and the simplest alkyne. This colorless gas is widely used as a fuel and a chemical building block. It is unstable in pure form and thus is usually handled as a solution.As an alkyne, acetylene is unsaturated because...
to give the "closo" ortho-carborane
Carborane
A carborane is a cluster composed of boron and carbon atoms. Like many of the related boranes, these clusters are polyhedra and are similarly classified as closo-, nido-, arachno-, hypho-, etc...
:
- B10H12·2L + C2H2 → C2B10H12 + 2 L + H2
It is a weak Brønsted acid. Monodeprotonation generates the anion [B10H13]−, with again a nido structure.
Applications
Decaborane has no significant applications, although it has often been investigated. Since the molecule decomposes in a plasma, yielding monoatomic boron ions, decaborane is potentially useful as a fuel for aneutronic fusionAneutronic fusion
Aneutronic fusion is any form of fusion power where neutrons carry no more than 1% of the total released energy. The most-studied fusion reactions release up to 80% of their energy in neutrons...
, and for low energy ion implantation
Ion implantation
Ion implantation is a materials engineering process by which ions of a material are accelerated in an electrical field and impacted into another solid. This process is used to change the physical, chemical, or electrical properties of the solid...
of boron in the manufacture of semiconductor
Semiconductor
A semiconductor is a material with electrical conductivity due to electron flow intermediate in magnitude between that of a conductor and an insulator. This means a conductivity roughly in the range of 103 to 10−8 siemens per centimeter...
s. It has also been considered for plasma
Plasma (physics)
In physics and chemistry, plasma is a state of matter similar to gas in which a certain portion of the particles are ionized. Heating a gas may ionize its molecules or atoms , thus turning it into a plasma, which contains charged particles: positive ions and negative electrons or ions...
-assisted chemical vapor deposition
Chemical vapor deposition
Chemical vapor deposition is a chemical process used to produce high-purity, high-performance solid materials. The process is often used in the semiconductor industry to produce thin films. In a typical CVD process, the wafer is exposed to one or more volatile precursors, which react and/or...
for the manufacture boron-containing thin film
Thin film
A thin film is a layer of material ranging from fractions of a nanometer to several micrometers in thickness. Electronic semiconductor devices and optical coatings are the main applications benefiting from thin film construction....
s. In fusion research, the neutron
Neutron
The neutron is a subatomic hadron particle which has the symbol or , no net electric charge and a mass slightly larger than that of a proton. With the exception of hydrogen, nuclei of atoms consist of protons and neutrons, which are therefore collectively referred to as nucleons. The number of...
-absorbing nature of boron has led to the use of these thin boron-rich films to "boronize" the walls of the tokamak
Tokamak
A tokamak is a device using a magnetic field to confine a plasma in the shape of a torus . Achieving a stable plasma equilibrium requires magnetic field lines that move around the torus in a helical shape...
vacuum vessel to reduce recycling of particles and impurities into the plasma and improve overall performance.
Decaborane was also developed as an additive to special high-performance rocket fuels. Its derivates were investigated as well, e.g. ethyl decaborane. One patented fuel composition included vinyl decaborane-polyester
Polyester
Polyester is a category of polymers which contain the ester functional group in their main chain. Although there are many polyesters, the term "polyester" as a specific material most commonly refers to polyethylene terephthalate...
copolymer. Vinyl decaborane ("dekene") is prepared by reacting decaborane with acetylene
Acetylene
Acetylene is the chemical compound with the formula C2H2. It is a hydrocarbon and the simplest alkyne. This colorless gas is widely used as a fuel and a chemical building block. It is unstable in pure form and thus is usually handled as a solution.As an alkyne, acetylene is unsaturated because...
.
Safety
Decaborane, like pentaboranePentaborane
Pentaborane, also called pentaborane to distinguish it from B5H11, is an inorganic compound with the formula B5H9. It is one of the most common boron hydride clusters, although it is a highly reactive compound. Because of its high reactivity toward oxygen, it was once evaluated as rocket or jet fuel...
, is a powerful toxin affecting central nervous system
Central nervous system
The central nervous system is the part of the nervous system that integrates the information that it receives from, and coordinates the activity of, all parts of the bodies of bilaterian animals—that is, all multicellular animals except sponges and radially symmetric animals such as jellyfish...
, although decaborane is less toxic than pentaborane. It can be absorbed through skin. It forms an explosive mixture with carbon tetrachloride
Carbon tetrachloride
Carbon tetrachloride, also known by many other names is the organic compound with the formula CCl4. It was formerly widely used in fire extinguishers, as a precursor to refrigerants, and as a cleaning agent...
, which caused an often quoted explosion in a Malta, NY
Malta, New York
Malta is a town in Saratoga County, New York, United States. The town is in the central part of the county and is south of Saratoga Springs. The population was 13,005 at the 2000 census.- History :The town was first settled before 1865....
manufacturing facility in 1948 when CCl4 was used to clean the equipment.
Further reading
- NIST Chemistry Webbook, decaborane, accessed 23 October 2006.
- National Pollutant Inventory, Boron and compounds, accessed 23 October 2006.
- Decaborane in Organic Synthesis
- Webelements, Compounds of boron, accessed 23 October 2006.