Bismuthine

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^o
_f(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.