Sodium nitride: Difference between revisions

{{distinguish|sodium nitrate|sodium nitrite|sodium azide}}

| Watchedfields = changed

| verifiedrevid = 451382465

| Name = Sodium nitride

| ImageFile = Rhenium-trioxide-unit-cell-3D-balls-A.png

| IUPACName = Sodium nitride

| CASNo_Ref = {{cascite|correct|??}}

| CASNo = 12136-83-3

| EINECS = 235-232-3

| SMILES = [Na]N([Na])[Na]

| SMILES2 = [Na+].[Na+].[Na+].[N-3]

| SMILES3 = [Na+].[Na][N-][Na]

| InChI=1/3Na.N

| InChIKey = ZOULLXMSYSKRPG-UHFFFAOYNA-N}}

| Section2 = {{Chembox Properties

| Formula = Na₃N

| MolarMass = 82.976 g/mol

| Appearance = reddish brown or dark blue solid

| MeltingPtC = 87

| MeltingPt_ref = <ref name="Jansen" />

| MeltingPt_notes= (decomposes)

| Solubility = reacts}}

| Section3 = {{Chembox Structure

| Coordination =

| CrystalStruct = Cubic, [[Pearson symbol|cP4]]<ref name="Sangster" />

| SpaceGroup = Pm{{overline|3}}m<ref name="Sangster" />

| MolShape =

}}

| Section4 = {{Chembox Thermochemistry

| DeltaGf =

| DeltaHc =

| DeltaHf = -151 J/mol<ref name="Sangster" />

| Entropy =

| HeatCapacity =

| OtherAnions = [[Sodium amide]]<br>[[Sodium imide]]

| OtherCations = [[Lithium nitride]]<br>[[Potassium nitride]]}}}}

'''Sodium nitride''' is the [[inorganic compound]] with the [[chemical formula]] Na₃N. In contrast to [[lithium nitride]] and some other [[nitride]]s, sodium nitride is an extremely unstable [[alkali metal]] [[nitride]]. It can be generated by combining atomic beams of [[sodium]] and [[nitrogen]] deposited onto a low-temperature [[sapphire]] substrate.<ref name=Jansen>{{cite journal|title=Synthesis and structure of Na₃N|author=Fischer, D., Jansen, M.|journal= Angew Chem|volume=41|issue=10|year=2002|pages=1755–1756 |doi=10.1002/1521-3773(20020517)41:10<1755::AID-ANIE1755>3.0.CO;2-C|pmid=19750706 }} {{cite journal|title=Synthesis and structure of K₃N|author1=Fischer, D. |author2=Cancarevic, Z. |author3=Schön, J. C. |author4=Jansen, M. Z. |journal=Z. Anorg. Allg. Chem.|volume= 630|issue=1|page=156|doi=10.1002/zaac.200300280|year=2004}}. [http://pubs.acs.org/cen/topstory/8020/8020notw9.html 'Elusive Binary Compound Prepared'] ''Chemical & Engineering News'' '''80''' No. 20 (20 May 2002)</ref>

It readily decomposes into its elements:

:<chem>2 Na3N -> 6 Na + N2</chem>

==Synthesis==

Sodium nitride can be synthesized in two different ways: by the [[thermal decomposition]] of [[sodium amide|NaNH₂]] or by the direct reaction of the elements.<ref name=Sangster>{{cite journal | title=N-Na(Nitrogen-Sodium) System | author=Sangster, J. | journal= Journal of Phase Equilibria and Diffusion | volume=25 | issue=6 | pages=560–563 | year=2004 | doi=10.1007/s11669-004-0082-0| s2cid=97905377 }}</ref> The most common way to successfully synthesize sodium nitride has been done by Dieter Fischer & Martin Jansen and Grigori Vajenine using the latter method. The first way is to introduce desired ratios of Na and N₂ in gas phase separately and depositing them in a vacuum chamber on a cooled substrate, which is then heated to room temperate (298 K) to crystallize.<ref name=Jansen/>

The second method is to react elemental sodium with plasma activated nitrogen on a metal surface. This synthesis can be further facilitated by introducing liquid Na-K alloy to the compound with the excess liquid removed and washed with fresh alloy. The solid is then separated from the liquid using a centrifuge. However Vajenine’s method is very air-sensitive and can decompose and combust rapidly, unless exposed to a pure oxygen (O₂) environment.<ref name=Plasma>{{cite journal | title=Plasma-Assisted Synthesis and Properties of Na₃N | author=Vajenine, G.V. | journal= Inorganic Chemistry | volume=46 | issue=13 | pages=5146–5148 | year=2007 | doi=10.1021/ic700406q| pmid=17530752 }}</ref>

==Characteristics==

Sodium nitride can be of reddish brown or dark blue color depending on the synthesis of the compound due to intrinsic properties.<ref name=Jansen/><ref name=Plasma/> It shows no signs of decomposition after several weeks when at room temperature.<ref name=Plasma/> The compound does not have a melting point as it decomposes back into its elemental forms as demonstrated using mass spectrometry around 360 K.<ref name=Jansen/><ref name=Sangster/> The estimated enthalpy of formation for the compound is +64 kJ/mol.<ref name=Plasma/>

==Structure==

Sodium nitride seems to be about 90% ionic at room temperature, but has the band gap typical for a semiconductor.<ref name=Sangster/><ref name=Plasma/> It adopts the anti-ReO₃ structure with a simple lattice made up of NNa₆ octahedra.<ref name=Jansen/><ref name=Sangster/><ref name=Plasma/><ref name=Distort>{{cite journal | title=A Temperature-dependent Structural Study of ''anti''-ReO₃-type Na₃N: to Distort or not to Distort? | author=Vajenine, G. V., Hoch, C., Dinnebier, R. E., Senyshyn, A., Niewa, R. | journal= Zeitschrift für Anorganische und Allgemeine Chemie | volume=636 | issue=1 | pages=94–99 | year=2009 | doi=10.1002/zaac.200900488}}</ref> The compound has N­−Na bond lengths of 236.6&nbsp;pm.<ref name=Jansen/><ref name=Plasma/> This structure has been confirmed through X-ray diffraction and more recently neutron diffraction on powder and single crystals.<ref name=Jansen/><ref name=Sangster/><ref name=Plasma/><ref name=Distort/>

{{Nitrides}}