Bismuthine (IUPAC name: bismuthane) is the chemical compound with the formula BiH<sub>3</sub>. As the heaviest analogue of ammonia (a pnictogen hydride), BiH<sub>3</sub> is unstable, decomposing to bismuth metal well below 0 ðC. This compound adopts the expected pyramidal structure with HâÂÂBiâÂÂH angles of around 90ð.
The term bismuthine may also refer to a member of the family of organobismuth(III) species having the general formula , where R is an organic substituent. For example, Bi(CH<sub>3</sub>)<sub>3</sub> is trimethylbismuthine.
BiH<sub>3</sub> is prepared by the redistribution of methylbismuthine (BiH<sub>2</sub>Me):
The required BiH<sub>2</sub>Me, which is also thermally unstable, is generated by reduction of methylbismuth dichloride, BiCl<sub>2</sub>Me with LiAlH<sub>4</sub>.
As suggested by the behavior of SbH<sub>3</sub>, BiH<sub>3</sub> is unstable and decomposes to its constituent elements according to the following equation:
The methodology used for detection of arsenic ("Marsh test") can also be used to detect BiH<sub>3</sub>. 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.
The low stability of BiH<sub>3</sub> precludes significant health effects, it decomposes rapidly well below room temperature.