Bismuthine

Bismuthine

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Names
IUPAC name bismuthane
Other names bismuth trihydride hydrogen bismuthide
Identifiers
CAS Number	18288-22-7 Y
ChemSpider	8886 N
Jmol 3D model	Interactive image
PubChem	9242
InChI InChI=1S/Bi.3H N Key: BPBOBPIKWGUSQG-UHFFFAOYSA-N 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
Vapor pressure	{{{value}}}
Related compounds
Related hydrides	Ammonia Phosphine Arsine Stibine
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Infobox references

Bismuthine (IUPAC name: bismuthane) is the chemical compound with the formula BiH₃. As the heaviest analogue of ammonia, 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°.

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):

3 BiH₂Me → 2 BiH₃ + BiMe₃

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

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.

Uses and safety considerations

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