Sodium phosphide
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2008-05-04T01:42:57Z
Benjah-bmm27
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[[space-filling model]] added
{{Chembox new
| ImageFile = Sodium-phosphide-xtal-3D-vdW.png
| Name = Sodium phosphide
| OtherNames = sodium phosphide, common</br>trisodiophosphine
| Section1 = {{Chembox Identifiers
| CASNo = 12058-85-4
}}
| Section2 = {{Chembox Properties
| Formula = Na<sub>3</sub>P
| MolarMass = 99.94 g/mol
| Appearance = black solid
| SolubleOther = insolubile in liquid CO<sub>2</sub>
}}<!--
| [[Enthalpy of Formation]]<sup>9</sup>
| -32.0 kcal/mol -->
| Section3 = {{Chembox Structure
| Coordination = around P 5 near neighbours, trigonal bipyramid <ref name = "Dong">Dong, Y.; DiSalvo, F.J. ''Acta. Crystallogr. Sect E: Struct. Rep. Online''. '''2005''', ''E61'', i223-i224.</ref>
| CrystalStruct = [[hexagonal]]</br> a = 4.9512 Å</br>c = 8.7874 Å
}}
| Section8 = {{Chembox Related
| OtherAnions = [[sodium chloride]]<br />sodium nitride
| OtherCations = [[aluminium phosphide]]<br />lithium phosphide
}}
}}
'''Sodium phosphide''', Na<sub>3</sub>P, is a black, [[ionic salt]] containing the [[alkali metal]] [[sodium]] and the [[phosphide]] [[anion]].<ref>Yunle, G.; Fan, G.; Yiate, Q.; Huagui, Z.; Ziping, Y. ''Mater. Res. Bull.'' '''2002''', ''37'', 1101-1106.</ref> Na<sub>3</sub>P is used in many chemical reactions requiring a highly reactive phosphide anion. It should not be confused with [[sodium phosphate]], Na<sub>3</sub>PO<sub>4</sub>.
In addition to Na<sub>3</sub>P there are five other binary phases of sodium and phosphorus; NaP, Na<sub>3</sub>P<sub>7</sub>, Na<sub>3</sub>P<sub>11</sub>, NaP<sub>7</sub> and NaP<sub>15</sub>.<ref> ''Inorganic Chemistry'',Egon Wiberg, Arnold Frederick Holleman Elsevier 2001 ISBN 0123526515</ref>
==Properties==
The structure of solid Na<sub>3</sub>P is the same as that of K<sub>3</sub>P. Each P atom has 5 near neighbours.<ref name = "Dong"/>
The structure of molecular '''sodium phosphide''' is similar to that of molecular lithium phosphide, Li<sub>3</sub>P, for both are [[trigonal pyramid (chemistry)|trigonal pyramidal]], with a lone pair of electrons on the central phosphorus atom. The ionic properties of Na<sub>3</sub>P are also similar to Li<sub>3</sub>P, which is known to be an ionic superconductor. The lowest energy conformation is the same for both molecules, non-planar C<sub>3v</sub> symmetry. Due to its unique structure, Na<sub>3</sub>P has the ability to invert itself. The inversion barrier energies for Na<sub>3</sub>P and Li<sub>3</sub>P are calculated to be 7.5 kcal/mol and 4.9 kcal/mol respectively.<ref>Francisco, J.S.; Khitrov, G. ''Chem. Phys.'' '''1993''', ''171'', 153-157.</ref>
==History==
Preparation of '''sodium phosphide''' originally began in the mid-19th century. French researcher, Alexandre Baudrimont prepared sodium phosphide by reacting molten sodium with [[phosphorus pentachloride]].<ref>Baudrimont. ''Ann. Chim. Phys.'' '''1864''', ''2'', 13.
</ref>
[[sodium|8Na<sub>(l)</sub>]] + [[phosphorus pentachloride|PCl<sub>5</sub>]] → [[sodium chloride|5NaCl]] + Na<sub>3</sub>P
==Preparation==
Since the original preparation was performed there have been many different ways of preparing '''sodium phosphide'''. Yellow [[phosphorus]] reacts with sodium in an autoclave at 150°C for 5 hours to produce Na<sub>3</sub>P. <ref>Xie, Y.; Su, H.; Li, B.; Qian, Y. ''Mater. Res. Bull.'' '''2000''', ''35'', 675-680.</ref>
P<sub>4</sub> + 12Na → 4Na<sub>3</sub>P
If the autoclave technique cannot be utilized the reactants may be placed under vacuum and heated from 30 minutes at 170°C, then 30 minutes at 350°C, and finally for 5 hours at 480°C.<ref>Jarvis, R.F.; Jacubinas, R.M.; Kaner, R.B. ''Inorg. Chem.'' '''2000''', ''39'', 3243-3246.</ref>
The previous two preparations require high temperatures, which are not always desirable. For this reaction to proceed at ambient conditions a [[catalyst]] is used. The catalyst used in one method was [[naphthalene]] due to its ability to form [[radical (chemistry)]] anions and dianions and act as an electron bridge for the binding of sodium to phosphorus.<ref>Peterson, D.J. '''1967'''. Patent No. 3,397,039.</ref>
==Uses==
'''Sodium phosphide''' has a variety of uses because it contains the highly reactive phosphide anion. Due to its flammability and toxicity, Na<sub>3</sub>P is prepared [[in situ]]. One such application is in the preparation of [[indium phosphide]], a nanoparticle superconductor. Na<sub>3</sub>P was prepared by reacting sodium metal and white phosphorus in ''N,N’''-dimethylformamide, [[DMF]]. [[Indium(III) chloride]] was then added to the reaction.<ref>Khanna, P.K.; Eum, M.-S.; Jun, K.-W.; Baeg,J.-O.; Seok, S. I. ''Mater. Lett.'' '''2003''', ''57'', 4617-4621.
</ref>
[[Image:InP formation.JPG|indium phosphide formation|{{pd-self}}]]
'''Sodium phosphide''' is also employed commercially as a [[catalyst]] in conjunction with zinc phosphide and [[aluminium phosphide]] for [[polymer]] production. When Na<sub>3</sub>P is removed from the ternary catalyst [[polymerization]] of [[propylene]] and 4-methyl-1-pentene is not effective.<ref>Atarashi, Y.; Fukumoto, O. Japanese Patent No. JP 42,006,269.</ref>
[[Image:Polymer rxn.JPG|polymerization of propene|{{pd-self}}]]
==Precautions==
There are inherent hazards when reacting sodium and any [[allotrope]] of phosphorus to produce '''sodium phosphide'''. The [[USDOT]] has forbidden the transportation of Na<sub>3</sub>P on passenger aircraft, cargo only aircraft, and trains due to the potential fire and toxic hazards.[http://environmentalchemistry.com/yogi/chemicals/cn/Sodium%A0phosphide.html] Therefore, no chemical company manufactures Na<sub>3</sub>P for distribution, and why processes requiring Na<sub>3</sub>P as reactant must obtain it in situ.
==References==
<references/>
<!---this ref not marked in line in the text Morozova, M.P.; Bol'shakova, G.A.; Lukinykh, N.L. ''Zh. Obsch. Khim.'' '''1959''', ''29'', 3144-3145.>
==External links==
*[http://environmentalchemsitry.com/yogi/chemicals/cn/Sodium%A0phosphide.html Environmental Chemistry Chemical Database- safety information for sodium phosphide from the U.S. Code of Federal Regulations]
[[Category:Phosphides]]