Stibine

Chembox new
Name = Stibine
ImageFile = Stibine.png ImageName = Stibine
ImageFile1 = Stibine-3D-vdW.png ImageName1 = Stibine
OtherNames = Antimony trihydride
stibane
Section1 = Chembox Identifiers
CASNo = 7803-52-3
Section2 = Chembox Properties
Formula = H₃Sb
MolarMass = 124.784 g/mol
Appearance = Colourless gas
Density = 5.48 g/L, gas.
Solvent = other solvents
SolubleOther = Insoluble
MeltingPt = −88 °C
BoilingPt = −17 °C
pKb =
Section3 = Chembox Structure
MolShape = Trigonal pyramidal
Dipole =
Section7 = Chembox Hazards
ExternalMSDS =
EUClass = Harmful (Xn)
Dangerous for
the environment (N)
NFPA-H = 4
NFPA-R = 2
NFPA-F = 4
RPhrases = R20/22, R50/53
SPhrases = S2, S61
FlashPt = Flammable gas
Section8 = Chembox Related
OtherCpds = Ammonia,
Phosphine,
Arsine
Bismuthine
Triphenylstibine

Stibine is the chemical compound with the formula SbH₃. This colourless gas is the principal covalent hydride of antimony and a heavy analogue of ammonia. The molecule is pyramidal with H–Sb–H angles of 91.7° and Sb–H distances of 1.707 Å (170.7 pm). This gas has an offensive smell like hydrogen sulfide (rotten eggs).

Preparation

SbH₃ is generally prepared by the reaction of Sb³⁺ sources with H⁻ equivalents: [cite journal | author = Bellama, J. M.; MacDiarmid, A. G. | title = Synthesis of the Hydrides of Germanium, Phosphorus, Arsenic, and Antimony by the Solid-Phase Reaction of the Corresponding Oxide with Lithium Aluminum Hydride | journal = Inorg. Chem. | year = 1968 | volume = 7| pages = 2070–2 | doi = 10.1021/ic50068a024] ::2 Sb₂O₃ + 3 LiAlH₄ → 4 SbH₃ + 1.5 Li₂O + 1.5 Al₂O₃::SbCl₃ + 3/4 NaBH₄ → SbH₃ + 0.75 NaCl + 0.75 BCl₃

Alternatively, sources of Sb³⁻ react with protonic reagents (even water) to also produce this unstable gas:::Na₃Sb + 3 H₂O → SbH₃ + 3 NaOH

Properties

The chemical properties of SbH₃ resemble those for AsH₃.Holleman, A. F.; Wiberg, E. "Inorganic Chemistry" Academic Press: San Diego, 2001] Typical for a heavy hydride (e.g. AsH₃, H₂Te, SnH₄), SbH₃ is unstable with respect to its elements. The gas decomposes slowly at room temperature but rapidly at 200 °C:::2 SbH₃ → 3 H₂ + 2 Sb The decomposition is autocatalytic and can be explosive.

SbH₃ is readily oxidized by O₂ or even air:::2 SbH₃ + 3 O₂ → Sb₂O₃ + 3 H₂O

SbH₃ exhibits no basicity, but it can be deprotonated:::SbH₃ + NaNH₂ → NaSbH₂ + NH₃

Uses

Stibine is used in the semiconductor industry to dope small quantities of antimony via the process of chemical vapour deposition (CVD). Reports claim the use of SbH₃ as a fumigant but its instability and awkward preparation contrast with the more conventional fumigant PH₃.

History

As stibine (SbH₃) is very similar to arsine (AsH₃), it is also detected by the Marsh test. This sensitive test detects arsine generated in the presence of arsenic. This procedure, developed around 1836 by James Marsh, is based upon treating a sample with arsenic-free zinc and dilute sulfuric acid: if the sample contains arsenic, gaseous arsine will form. The gas is swept into a glass tube and decomposed by means of heating around 250–300 °C. The presence of arsenic is indicated by formation of a deposit in the heated part of the equipment. The formation of a black mirror deposit in the cool part of the equipment indicates the presence of antimony.

In 1837 Lewis Thomson and Pfaff independently discovered stibine. It took some time before the properties of the toxic case could be determined, partly because a suitable synthesis was not available. In 1876 Francis Jones tested several synthesis methods, [cite journal
author= Francis Jones
title = On stibine
journal = Journal of the Chemical Society
year = 1876
volume = 29
issue = 2
pages = 641
doi = 10.1039/JS8762900641] but it was not before 1901 when Alfred Stock determined most of the properties of stibine. [cite journal
author= Alfred Stock, Walther Doht
title = Die Reindarstellung des Antimonwasserstoffes
journal = Berichte der deutschen chemischen Gesellschaft
year = 1901
volume = 34
issue = 2
pages = 2339–2344
doi = 10.1002/cber.190103402166] [cite journal
author= Alfred Stock, Oskar Guttmann
title = Ueber den Antimonwasserstoff und das gelbe Antimon
journal = Berichte der deutschen chemischen Gesellschaft
year = 1904
volume = 37
issue = 1
pages = 885–900
doi = 10.1002/cber.190403701148]

afety

SbH₃ is an unstable flammable gas. It is highly toxic, with an LC50 of 100 ppm in mice. Fortunately, SbH₃ is so unstable that it is rarely encountered outside of laboratories.

Toxicology

:"For the toxicology of other antimony compounds, see Antimony trioxide."The toxicity of stibine is distinct from that of other antimony compounds, but similar to that of arsine. [Institut national de recherche et de sécurité (INRS), "Fiche toxicologique n° 202 : Trihydrure d'antimoine", 1992.] Stibine binds to the haemoglobin of red blood cells, causing them to be destroyed by the body. Most cases of stibine poisoning have been accompanied by arsine poisoning, although animal studies indicate that their toxicities are equivalent. The first signs of exposure, which can take several hours to become apparent, are headaches, vertigo and nausea, followed by the syptoms of hemolytic anemia (high levels of unconjugated bilirubin), hemoglobinuria and nephropathy.

References

External links

* [http://www.ilo.org/public/english/protection/safework/cis/products/icsc/dtasht/_icsc07/icsc0776.htm International Chemical Safety Card 0776]
* [http://www.cdc.gov/niosh/npg/npgd0568.html NIOSH Pocket Guide to Chemical Hazards]
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