Phosphine

Synonyms

Hydrogen phosphide; Phosphorus hydride

Definition

Phosphine, PH₃, is a toxic, phosphorus gas at standard temperature and pressure, boiling at 185 K and freezing below 135 K. Relative to phosphate, the redox state of the phosphorus atom in phosphine is reduced to −3. Phosphine is the most abundant, naturally occurring volatile phosphorus species, and has been detected in the atmospheres of the gas giants Jupiter and Saturn, in the atmospheric envelopes of giant stars, and as a trace constituent in the atmosphere of the Earth. Its terrestrial origin may be linked to microbial activity or to anthropogenic sources; hence, phosphine plays a small role in the phosphorus biogeochemical cycle. At low temperatures (below 70–80 K), it can be trapped as a clathrate in water ice.