Bismuthine (IUPAC name: bismuthane) is the
chemical compound
A chemical compound is a chemical substance composed of many identical molecules (or molecular entities) containing atoms from more than one chemical element held together by chemical bonds. A molecule consisting of atoms of only one element ...
with the formula
Bi H3. As the heaviest analogue of
ammonia
Ammonia is an inorganic chemical compound of nitrogen and hydrogen with the chemical formula, formula . A Binary compounds of hydrogen, stable binary hydride and the simplest pnictogen hydride, ammonia is a colourless gas with a distinctive pu ...
(a
pnictogen hydride
Pnictogen hydrides or hydrogen pnictides are binary compounds of hydrogen with pnictogen ( or ; from "to choke" and -gen, "generator") atoms (elements of group 15: nitrogen, phosphorus, arsenic, antimony, bismuth, and moscovium) covalently bonded ...
), BiH
3 is unstable, decomposing to
bismuth
Bismuth is a chemical element; it has symbol Bi and atomic number 83. It is a post-transition metal and one of the pnictogens, with chemical properties resembling its lighter group 15 siblings arsenic and antimony. Elemental bismuth occurs nat ...
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 , where R is an organic substituent. For example, Bi(CH
3)
3 is ''trimethylbismuthine''.
Preparation and properties
BiH
3 is prepared by the redistribution of methylbismuthine (BiH
2Me):
[Holleman, A. F.; Wiberg, E. "Inorganic Chemistry" Academic Press: San Diego, 2001..]
:3 BiH
2Me → 2 BiH
3 + BiMe
3
The required BiH
2Me, which is also thermally unstable, is generated by reduction of
methylbismuth dichloride, BiCl
2Me with
LiAlH4.
As suggested by the behavior of
SbH3, BiH
3 is unstable and decomposes to its constituent elements according to the following equation:
:2 BiH
3 → 3 H
2 + 2 Bi (Δ''H''(gas) = −278 kJ/mol)
The methodology used for detection of
arsenic
Arsenic is a chemical element; it has Symbol (chemistry), symbol As and atomic number 33. It is a metalloid and one of the pnictogens, and therefore shares many properties with its group 15 neighbors phosphorus and antimony. Arsenic is not ...
("
Marsh test
The Marsh test is a highly sensitive method in the detection of arsenic, especially useful in the field of forensic toxicology when arsenic was used as a poison. It was developed by the chemist James Marsh and first published in 1836. The meth ...
") can also be used to detect BiH
3. This test relies on the
thermal decomposition
Thermal decomposition, or thermolysis, is a chemical decomposition of a substance caused by heat. The decomposition temperature of a substance is the temperature at which the substance chemically decomposes. The reaction is usually endothermic ...
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 precludes significant health effects, it decomposes rapidly well below room temperature.
References
{{Hydrides by group
Bismuth compounds
Metal hydrides
Bismuthides