Sodium phosphide

Sodium phosphide
Names
Other names
sodium phosphide, common
trisodiophosphine
Identifiers
12058-85-4 
ChemSpider 55463 Yes
EC number 235-031-0
Jmol-3D images Image
PubChem 61547
Properties
Na3P
Molar mass 99.943 g/mol
Appearance red crystals
Density 1.74 g/cm3
Melting point 650 °C (1,202 °F; 923 K)
hydrolysis
Solubility insoluble in liquid CO2
Structure
Crystal structure hexagonal
a = 4.9512 Å
c = 8.7874 Å
around P 5 near neighbours, trigonal bipyramid [1]
Related compounds
Other anions
sodium chloride
sodium nitride
Other cations
aluminium phosphide
lithium phosphide
potassium phosphide
Except where noted otherwise, data is given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
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Infobox references

Sodium phosphide, Na3P, is a black, ionic salt containing the alkali metal sodium and the phosphide anion.[2] Na3P is a source of the highly reactive phosphide anion. It should not be confused with sodium phosphate, Na3PO4.

In addition to Na3P, five other binary compositions of sodium and phosphorus are known: NaP, Na3P7, Na3P11, NaP7, and NaP15.[3]

Properties

Like K3P, solid Na3P features pentacoordinate P centers.[1] In the gas phase, molecular Na3P and Li3P are both trigonal pyramidal, with a lone pair of electrons on the central phosphorus atom.

Preparation

The first preparation of Na3P was first reported in the mid-19th century. French researcher, Alexandre Baudrimont prepared sodium phosphide by reacting molten sodium with phosphorus pentachloride.[4]

8 Na(l) + PCl55NaCl + Na3P

Many different routes to Na3P have been described. Due to its flammability and toxicity, Na3P (and related salts) are generally prepared in situ. White phosphorus is reduced by sodium-potassium alloy to give the phosphide salt.[5]

The conversion of white phosphorus to the phosphide has been well studied. Phosphorus reacts with sodium in an autoclave at 150 °C for 5 hours to produce Na3P.[6]

P4 + 12 Na → 4 Na3P

Alternatively the reaction can be conducted at normal pressures but using a temperatures gradient to generate nonvolatile NaxP phases (x < 3) that then react further with sodium.[7] In some cases, an electron-transfer agent, such as naphthalene, is used. In such applications, the naphthalene forms the soluble radical anions and more rapidly reduces the phosphorus.[8]

Uses

Sodium phosphide is a source of the highly reactive phosphide anion. The material is insoluble in all solvents but reacts as a slurry with acids and related electrophiles to give derivatives of the type PM3:[5]

Na3P + 3 M+5 → M3P (M = H, Me3Si)

The trimethylsilyl derivative is volatile (b.p. 30-35 C @ 0.001 mm Hg) and soluble. It serves as a soluble equivalent to "P3−".

Indium phosphide, a semiconductor arises by treating in-situ generated "sodium phosphide" with indium(III) chloride in hot N,N’-dimethylformamide as solvent. In this process, the phosphide reagent is generated from sodium metal and white phosphorus, whereupon it immediately reacts with the indium salt:[9]

3Na + P → Na3P
Na3P + InCl3 → InP + 3NaCl

Sodium phosphide is also employed commercially as a catalyst in conjunction with zinc phosphide and aluminium phosphide for polymer production. When Na3P is removed from the ternary catalyst polymerization of propylene and 4-methyl-1-pentene is not effective.[10]

polymerization of propene

Precautions

Sodium phosphide is highly dangerous releasing toxic phosphine upon hydrolysis, a process that is so exothermic that fires result. The USDOT has forbidden the transportation of Na3P on passenger aircraft, cargo only aircraft, and trains due to the potential fire and toxic hazards.[11]

References

  1. 1.0 1.1 Dong, Y; Disalvo, F.J (2005). "Reinvestigation of Na3P based on single-crystal data". Acta Crystallogr. E 61 (11): i223–i224. doi:10.1107/S1600536805031168.
  2. Yunle, G; Fan, G; Yiate, Q; Huagui, Z; Ziping, Y (2002). "A solvothermal synthesis of ultra-fine iron phosphide". Mater. Res. Bull. 37 (6): 1101–1106. doi:10.1016/S0025-5408(02)00749-3.
  3. Inorganic Chemistry, Egon Wiberg, Arnold Frederick Holleman Elsevier 2001 ISBN 0-12-352651-5
  4. Baudrimont (1864). Ann. Chim. Phys. 2: 13. Missing or empty |title= (help)
  5. 5.0 5.1 Becker, Gerd; Schmidt, Helmut; Uhl, Gudrun (1990). "Tris(Trimethylsilyl)Phosphine and Lithium Bis(Trimethylsilyl)Phosphide.Bis-(Tetrahydrofuran)". Inorganic Syntheses 27: 243–249. doi:10.1002/9780470132586.ch48.
  6. Xie, Y; Su, H; Li, B; Qian, Y (2000). "Solvothermal preparation of tin phosphide nanorods". Mater. Res. Bull. 35 (5): 675–680. doi:10.1016/S0025-5408(00)00263-4.
  7. Jarvis, R.F; Jacubinas, R.M; Kaner, R.B (2000). "Self-Propagating Metathesis Routes to Metastable Group 4 Phosphides". Inorg. Chem. 39 (15): 3243–3246. doi:10.1021/ic000057m. PMID 11196860.
  8. Peterson, D.J. 1967. Patent No. 3,397,039.
  9. Khanna, P.K; Eum, M.-S; Jun, K.-W; Baeg, J.-O; Seok, S. I (2003). "A novel synthesis of indium phosphide nanoparticles". Mater. Lett. 57 (30): 4617–4621. doi:10.1016/S0167-577X(03)00371-9.
  10. Atarashi, Y.; Fukumoto, O. Japanese Patent No. JP 42,006,269.
  11. http://environmentalchemistry.com/yogi/chemicals/cn/Sodium%A0phosphide.html


External links