Bismuthine

Bismuthine

Names
IUPAC name bismuthane
Other names bismuth trihydride hydrogen bismuthide bismine
Identifiers
CAS Number	18288-22-7
3D model (Jmol)	Interactive image
ChemSpider	8886
PubChem	9242
InChI InChI=1S/Bi.3H Key: BPBOBPIKWGUSQG-UHFFFAOYSA-N InChI=1/Bi.3H/rBiH3/h1H3 Key: BPBOBPIKWGUSQG-PVKOQVOWAF
SMILES [Bi]
Properties
Chemical formula	BiH3
Molar mass	212.00 g/mol
Appearance	colourless gas
Density	0.008665 g/mL (20 °C)
Boiling point	16.8 °C (62.2 °F; 289.9 K) (extrapolated)
Structure
Molecular shape	trigonal pyramidal
Related compounds
Related hydrides	Ammonia Phosphine Arsine Stibine
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Bismuthine (IUPAC name: bismuthane) is the chemical compound with the formula BiH₃. As the heaviest analogue of ammonia (a pnictogen hydride), BiH₃ is unstable, decomposing to bismuth metal well below 0 °C. This compound adopts the expected pyramidal structure with H-Bi-H angles of around 90°.^[1]

The term bismuthine may also refer to a member of the family of organobismuth(III) species having the general formula BiR
3, where R is an organic substituent. For example, Bi(CH₃)₃ is trimethylbismuthine.

Preparation and properties

BiH₃ is prepared by the redistribution of methylbismuthine (BiH₂Me):^[2]

3 BiH₂Me → 2 BiH₃ + BiMe₃

The required BiH₂Me, which is also thermally unstable, is generated by reduction of methylbismuth dichloride, BiCl₂Me with LiAlH₄.^[1]

As suggested by the behavior of SbH₃, BiH₃ is unstable and decomposes to its constituent elements according to the following equation:

2 BiH₃ → 3 H₂ + 2 Bi (ΔH_f'^o_gas = −278 kJ/mol)

The methodology used for detection of arsenic ("Marsh test") can also be used to detect BiH₃. This test relies on the thermal decomposition of these trihydrides to the metallic mirrors of reduced As, Sb, and Bi. These deposits can be further distinguished by their distinctive solubility characteristics: arsenic dissolves in NaOCl, antimony dissolves in ammonium polysulfide, and bismuth resists both reagents.^[2]

Uses and safety considerations

The low stability of BiH₃ poses significant hazards and precludes technical applications, except as an intermediary product.

References

1. W. Jerzembeck; H. Bürger; L. Constantin; L. Margulès; J. Demaison; J. Breidung; W. Thiel (2002). "Bismuthine BiH₃: Fact or Fiction? High-Resolution Infrared, Millimeter-Wave, and Ab Initio Studies". Angew. Chem. Int. Ed. 41 (14): 2550–2552. doi:10.1002/1521-3773(20020715)41:14<2550::AID-ANIE2550>3.0.CO;2-B.
2. Holleman, A. F.; Wiberg, E. "Inorganic Chemistry" Academic Press: San Diego, 2001.ISBN 0-12-352651-5.