Sodium phosphide

Sodium phosphide

Names
Other names sodium phosphide, trisodiophosphine
Identifiers
CAS Number	12058-85-4 Y
3D model (JSmol)	Interactive image
ChemSpider	55463 Y
ECHA InfoCard	100.031.834
EC Number	235-031-0
PubChem CID	61547
UNII	A360RQX9W2 Y
InChI InChI=1S/3Na.P/q3*+1;-3 Y Key: FHHBFSHDCCEUKM-UHFFFAOYSA-N Y InChI=1/3Na.P/q3*+1;-3 Key: FHHBFSHDCCEUKM-UHFFFAOYAE
SMILES [Na+].[Na+].[Na+].[P-3]
Properties
Chemical formula	Na3P
Molar mass	99.943 g/mol
Appearance	red crystals
Density	1.74 g/cm3
Melting point	650 °C (1,202 °F; 923 K)
Solubility in water	hydrolysis
Solubility	insoluble in liquid CO2
Structure
Crystal structure	hexagonal a = 4.9512 Å c = 8.7874 Å
Coordination geometry	around P 5 near neighbours, trigonal bipyramid [1]
Related compounds
Other anions	sodium arsenide sodium nitride
Other cations	aluminium phosphide lithium phosphide potassium phosphide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). N verify (what is YN ?) Infobox references

Sodium phosphide is the inorganic compound with the formula Na₃P. It is a black solid. It is often described as Na⁺ salt of the P³⁻ 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]

The compound crystallizes in a hexagonal motif, often called the sodium arsenide structure.^[4] Like K₃P, solid Na₃P features pentacoordinate P centers.^[1]

The first preparation of Na₃P was first reported in the mid-19th century. French researcher, Alexandre Baudrimont prepared sodium phosphide by treating molten sodium with phosphorus pentachloride.^[5]

8 Na_(l) + PCl₅ → 5 NaCl + Na₃P

Many different routes to Na₃P have been described. Due to its flammability and toxicity, Na₃P (and related salts) is often prepared and used in situ. White phosphorus is reduced by sodium-potassium alloy:^[6]

P₄ + 12 Na → 4 Na₃P

Phosphorus reacts with sodium in an autoclave at 150 °C for 5 hours to produce Na₃P.^[7]

Alternatively the reaction can be conducted at normal pressures but using a temperatures gradient to generate nonvolatile Na_xP phases (x < 3) that then react further with sodium.^[8] In some cases, an electron-transfer agent, such as naphthalene, is used. In such applications, the naphthalene forms the soluble sodium naphthalenide, which reduces the phosphorus.^[9]

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:^[6]

Na₃P + 3 E⁺ → E₃P (E = 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:^[10]

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.^{[11][citation needed]}

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 aircraft and trains due to the potential fire and toxic hazards.^[12]