Stibine

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Stibine

General
Systematic name	Stibane
Other names	Antimony trihydride
Molecular formula	SbH₃
Molar mass	124.784 g/mol
Appearance	Colourless gas
CAS number	[7803-52-3] [1]
Properties
Density and phase	5.48 g/l, gas.
Solubility (water)	Insoluble
Melting point	-88°C
Boiling point	-17°C
Basicity (pK_b)	?
Structure
Molecular shape	Trigonal pyramidal
Dipole moment	? D
ΔH'_f'^o_gas	145.2 kJ/mol
Hazards
MSDS	External MSDS
EU classification	Harmful (Xn) Dangerous for the environment (N)
NFPA 704	4 4 2
R-phrases	R20/22, R50/53
S-phrases	S2, S61
Flash point	Flammable gas
Supplementary data page
Structure and properties	n, ε_r, etc.
Thermodynamic data	Phase behaviour Solid, liquid, gas
Spectral data	UV, IR, NMR, MS
Related compounds
Related hydrides	Ammonia, Phosphine, Arsine Bismuthine
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references

Stibine, also called stibane or antimony trihydride, is 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.

1 Preparation and properties
2 Uses
3 Safety
4 Toxicology
5 Bibliography
6 External links

[edit] Preparation and properties

SbH₃ is generally prepated by the reaction of Sb³⁺ sources with H⁻ equivalents:↑

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

The chemical properties of SbH₃ resemble those for AsH₃.^[2] 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

[edit] 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.

[edit] Safety

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

[edit] 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.↑ 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.

[edit] Bibliography

↑ Bellama, J. M.; MacDiarmid, A. G. "Synthesis of the Hydrides of Germanium, Phosphorus, Arsenic, and Antimony by the Solid-Phase Reaction of the Corresponding Oxide with Lithium Aluminum Hydride" Inorganic Chemistry, 1968, vol. 7, page 2070-2.
↑ Holleman, A. F.; Wiberg, E. "Inorganic Chemistry" Academic Press: San Diego, 2001.
↑ Institut national de recherche et de sécurité (INRS), Fiche toxicologique nº 202 : Trihydrure d'antimoine, 1992.