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 BiH
3. As the heaviest analogue of
ammonia
Ammonia is an inorganic compound of nitrogen and hydrogen with the formula . A stable binary hydride, and the simplest pnictogen hydride, ammonia is a colourless gas with a distinct pungent smell. Biologically, it is a common nitrogenous wa ...
(a
pnictogen hydride Pnictogen hydrides or hydrogen pnictides are binary compounds of hydrogen with pnictogen ( or ; from grc, πνῑ́γω "to choke" and -gen, "generator") atoms (elements of group 15: nitrogen, phosphorus, arsenic, antimony, and bismuth) covalently ...
), BiH
3 is unstable, decomposing to
bismuth
Bismuth is a chemical element with the 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 ...
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 with the symbol As and atomic number 33. Arsenic occurs in many minerals, usually in combination with sulfur and metals, but also as a pure elemental crystal. Arsenic is a metalloid. It has various allotropes, ...
("
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 metho ...
") can also be used to detect BiH
3. This test relies on the
thermal decomposition
Thermal decomposition, or thermolysis, is a chemical decomposition caused by heat. The decomposition temperature of a substance is the temperature at which the substance chemically decomposes. The reaction is usually endothermic as heat is re ...
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
Sodium hypochlorite (commonly known in a dilute solution as bleach) is an inorganic chemical compound with the formula NaOCl (or NaClO), comprising a sodium cation () and a hypochlorite anion (or ). It may also be viewed as the sodium salt o ...
, 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