Chemistry:Sodium nitride

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Sodium nitride
Rhenium-trioxide-unit-cell-3D-balls-A.png
Names
IUPAC name
Sodium nitride
Identifiers
3D model (JSmol)
EC Number
  • 235-232-3
Properties
Na3N
Molar mass 82.976 g/mol
Appearance reddish brown or dark blue solid
Melting point 87 °C (189 °F; 360 K)[1] (decomposes)
reacts
Structure
Cubic, cP4[2]
Pm3m[2]
Thermochemistry
-151 J/mol[2]
Related compounds
Other anions
Sodium amide
Sodium imide
Other cations
Lithium nitride
Potassium nitride
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Sodium nitride is the inorganic compound with the chemical formula Na3N. In contrast to lithium nitride and some other nitrides, 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.[1] It readily decomposes into its elements:

[math]\ce{ 2 Na3N -> 6 Na + N2 }[/math]

Synthesis

Sodium nitride can be synthesized in two different ways: by the thermal decomposition of NaNH2 or by the direct reaction of the elements.[2] 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.[1] 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.[3]

Characteristics

Sodium nitride can be of reddish brown or dark blue color depending on the synthesis of the compound due to intrinsic properties.[1][3] It shows no signs of decomposition after several weeks when at room temperature.[3] The compound does not have a melting point as it decomposes back into its elemental forms as demonstrated using mass spectrometry around 360 K.[1][2] The estimated enthalpy of formation for the compound is +64 kJ/mol.[3]

Structure

Sodium nitride seems to be about 90% ionic at room temperature, but has the band gap typical for a semiconductor.[2][3] It adopts the anti-ReO3 structure with a simple lattice made up of NNa6 octahedra.[1][2][3][4] The compound has N­−Na bond lengths of 236.6 pm.[1][3] This structure has been confirmed through X-ray diffraction and more recently neutron diffraction on powder and single crystals.[1][2][3][4]

References

  1. 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 Fischer, D., Jansen, M. (2002). "Synthesis and structure of Na3N". Angew Chem 41 (10): 1755–1756. doi:10.1002/1521-3773(20020517)41:10<1755::AID-ANIE1755>3.0.CO;2-C. PMID 19750706.  Fischer, D.; Cancarevic, Z.; Schön, J. C.; Jansen, M. Z. (2004). "Synthesis and structure of K3N". Z. Anorg. Allg. Chem. 630 (1): 156. doi:10.1002/zaac.200300280. . 'Elusive Binary Compound Prepared' Chemical & Engineering News 80 No. 20 (20 May 2002)
  2. 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 Sangster, J. (2004). "N-Na(Nitrogen-Sodium) System". Journal of Phase Equilibria and Diffusion 25 (6): 560–563. doi:10.1007/s11669-004-0082-0. 
  3. 3.0 3.1 3.2 3.3 3.4 3.5 3.6 3.7 Vajenine, G.V. (2007). "Plasma-Assisted Synthesis and Properties of Na3N". Inorganic Chemistry 46 (13): 5146–5148. doi:10.1021/ic700406q. PMID 17530752. 
  4. 4.0 4.1 Vajenine, G. V., Hoch, C., Dinnebier, R. E., Senyshyn, A., Niewa, R. (2009). "A Temperature-dependent Structural Study of anti-ReO3-type Na3N: to Distort or not to Distort?". Zeitschrift für Anorganische und Allgemeine Chemie 636 (1): 94–99. doi:10.1002/zaac.200900488. 
Salts and covalent derivatives of the nitride ion
NH3 He(N2)11
Li3N Be3N2 BN β-C3N4
g-C3N4
N2 NxOy NF3 Ne
Na3N Mg3N2 AlN Si3N4 PN
P3N5
SxNy
SN
S4N4
NCl3 Ar
K3N Ca3N2 ScN TiN VN CrN
Cr2N
MnxNy FexNy CoN Ni3N CuN Zn3N2 GaN Ge3N4 As Se NBr3 Kr
Rb3N Sr3N2 YN ZrN NbN β-Mo2N Tc Ru Rh PdN Ag3N CdN InN Sn Sb Te NI3 Xe
Cs3N Ba3N2   Hf3N4 TaN WN Re Os Ir Pt Au Hg3N2 TlN Pb BiN Po At Rn
Fr3N Ra3N   Rf Db Sg Bh Hs Mt Ds Rg Cn Nh Fl Mc Lv Ts Og
La CeN Pr Nd Pm Sm Eu GdN Tb Dy Ho Er Tm Yb Lu
Ac Th Pa UN Np Pu Am Cm Bk Cf Es Fm Md No Lr