Lithium phosphide

Lithium phosphide is an inorganic compound of lithium and phosphorus with the chemical formula Li₃P. This dark colored compound is formally the lithium salt of phosphine, consisting of lithium cations Li⁺ and phosphide anions P³⁻. It is hazardous to handle because of its high reactivity toward air.^[1]

Lithium phosphide

Names
Other names Trilithium phosphide
Identifiers
CAS Number	12057-29-3
3D model (JSmol)	Interactive image
ChemSpider	74796
ECHA InfoCard	100.031.824
EC Number	235-020-0
PubChem CID	25199615
CompTox Dashboard (EPA)	DTXSID4065232
InChI InChI=1S/3Li.H2P/h;;;1H2/q3*+1;-1 Key: IEAMEDSGNMSUND-UHFFFAOYSA-N
SMILES [Li+].[Li+].[Li+].[P-3]
Properties
Chemical formula	Li3P
Molar mass	51.79 g·mol−1
Appearance	Red-brown crystals
Density	1.43 g/cm3
Solubility in water	Reacts
Structure
Crystal structure	cubic
Related compounds
Other anions	Lithium nitride Lithium arsenide
Other cations	Sodium phosphide Calcium phosphide Aluminium phosphide Scandium phosphide Lanthanum phosphide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Synthesis

Heating red phosphorus and lithium in an argon atmosphere:^[1]

12 Li + P₄ → 4 Li₃P

Reaction of monolithium phosphide and lithium:

LiP + 2 Li → Li₃P

Physical and chemical properties

Lithium phosphide forms red-brown crystals of hexagonal systems, space group P6₃/mmc,^[2] cell parameters a = 0.4264 nm, c = 0.7579 nm, Z = 2.^[3][4]

The compound reacts with water to release phosphine:^[5]

Li₃P + 3 H₂O → 3 LiOH + PH₃

Uses

The compound is proposed to be used as a potential electrolyte for solid-state devices.^[6]

Related compounds

Reaction of lithium with red phosphorus at 870 °C gives Li₃P₇.^[7]

Further reading

• Nazri, Gholamabbas (1 April 1989). "Preparation, structure and ionic conductivity of lithium phosphide". Solid State Ionics. 34 (1–2): 97–102. doi:10.1016/0167-2738(89)90438-4.

Safety

Alkali metal phosphides are dangerous compounds when exposed to oxygen or moisture.^[8]

References

1. E. Donges (1963). "Phosphides, Arsenides, Antimonides and Bismuthides of Alkali Metals from the Elements". In G. Brauer (ed.). Handbook of Preparative Inorganic Chemistry, 2nd Ed. Vol. 2. NY, NY: Academic Press. p. 985.
2. "mp-736: Li3P (hexagonal, P6_3/mmc, 194)". materialsproject.org. Retrieved 10 December 2021.
3. Seel, Max; Pandey, Ravi (1990). "Band Structure and Electronic Properties of Lithium Phosphide Li3P". MRS Proceedings. 210. doi:10.1557/PROC-210-155. Retrieved 10 December 2021.
4. Donnay, Joseph Désiré Hubert (1963). Crystal Data; Determinative Tables. American Crystallographic Association. p. 765. Retrieved 10 December 2021.
5. Dong, Yongkwan; DiSalvo, Francis J. (15 April 2007). "Reinvestigation of trilithium phosphide, Li 3 P". Acta Crystallographica Section E. 63 (4): i97 – i98. doi:10.1107/S1600536807008422.
6. Wan, Chaoying; Huang, Xingyi; Bowen, Chris (23 June 2021). Two-dimensional Inorganic Nanomaterials for Conductive Polymer Nanocomposites. Royal Society of Chemistry. ISBN 978-1-83916-260-2. Retrieved 10 December 2021.
7. Manriquez, V.; Hönle, W.; von Schnering, H. G. (1986). "Zur Chemie und Strukturchemie von Phosphiden und Polyphosphiden. 42. Trilithiumheptaphosphid Li₃P₇: Darstellung, Struktur und Eigenschaften". Zeitschrift für Anorganische und Allgemeine Chemie. 539 (8): 95–109. doi:10.1002/zaac.19865390810.
8. Toxic Substances Control Act (TSCA) Chemical Substance Inventory. U.S. Government Printing Office. 1979. p. 9. Retrieved 10 December 2021.