Decaborane, also called decaborane(14), is the borane with the chemical formula B10H14.
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,
with a foul smelling odor.
== Handling properties and structure == The physical characteristics of decaborane(14)
resemble those of naphthalene and anthracene, all three of which are volatile colorless
solids. Sublimation is the common method of purification. 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 solvents.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 pyrolysis
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.It reacts with Lewis
bases (L) such as CH3CN and Et2S, to form adducts:
B10H14 + 2 L → B10H12L2 + H2These species, which are classified as "arachno" clusters,
in turn react with acetylene to give the "closo" ortho-carborane:
B10H12·2L + C2H2 → C2B10H12 + 2 L + H2Decaborane(14) is a weak Brønsted acid. Monodeprotonation
generates the anion [B10H13]−, with again a nido structure.
== Applications == Decaborane has no significant applications,
although the compound has often been investigated. Since the molecule decomposes in a plasma,
yielding monatomic boron ions, decaborane is potentially useful as a fuel for aneutronic
fusion. In 2018, LPP Fusion announced plans for using the material in its next round of
fusion experiments. Decaborane has been assessed for low energy ion implantation of boron in
the manufacture of semiconductors. It has also been considered for plasma-assisted chemical
vapor deposition for the manufacture of boron-containing thin films. 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.
Decaborane is an effective reagent for the reductive amination of ketones and aldehydes.
== Safety == Decaborane, like pentaborane, is a powerful
toxin affecting the central nervous system, 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, which caused an often-mentioned explosion in a manufacturing
facility