Stibine

Stibine is the chemical compound with the formula SbH₃. This colourless gas is the principal covalent hydride of antimony and a heavy analogue of ammonia. The molecule is pyramidal with H–Sb–H angles of 91.7° and Sb–H distances of 1.707 Å (170.7 pm). This gas has an offensive smell like hydrogen sulfide (rotten eggs).

Preparation

SbH₃ is generally prepared by the reaction of Sb³⁺ sources with H⁻ equivalents:

Alternatively, sources of Sb³⁻ react with protonic reagents (even water) to also produce this unstable gas:

Properties

The chemical properties of SbH₃ resemble those for AsH₃. Typical for a heavy hydride (e.g. AsH₃, H₂Te, SnH₄), SbH₃ is unstable with respect to its elements. The gas decomposes slowly at room temperature but rapidly at 200 °C:

The decomposition is autocatalytic and can be explosive.

SbH₃ is readily oxidized by O₂ or even air:

SbH₃ exhibits no basicity, but it can be deprotonated:

Uses

Stibine is used in the semiconductor industry to dope silicon with small quantities of antimony via the process of chemical vapour deposition (CVD). It has also been used as a silicon dopant in epitaxial layers. Reports claim the use of SbH₃ as a fumigant but its instability and awkward preparation contrast with the more conventional fumigant phosphine.