Lithium nitride

Crystal structure
__ Li +      __ N 3−
Crystal system	hexagonal
Space group	P 6 / mmm (No. 191)
General
Surname	Lithium nitride
Ratio formula	Li 3 N
Brief description	red-brown solid with an ammonia-like odor
External identifiers / databases
CAS number 26134-62-3 EC number 247-475-2 ECHA InfoCard 100.043.144 PubChem 520242 ChemSpider 453793 Wikidata Q413407
properties
Molar mass	34.83 g mol −1
Physical state	firmly
density	1.294 g cm −3
Melting point	813 ° C
solubility	reacts violently with water
safety instructions
GHS labeling of hazardous substances danger H and P phrases H: 260-314 P: 223-231 + 232-280-305 + 351 + 338-370 + 378-422
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Lithium nitride , Li ₃ N, is a chemical compound made up of lithium and nitrogen . In addition to Li ₃ N, other lithium nitrides are known (at sometimes high pressures) with LiN ₂ , LiN and LiN ₅ .

synthesis

Lithium nitride is made by reacting lithium with nitrogen. The reaction already takes place at room temperature, but very slowly, so that higher temperatures are usually used for the synthesis of lithium nitride:

${\displaystyle \mathrm {6\ Li\ +N_{2}\ {\xrightarrow {100^{\circ }C}}\ 2\ Li_{3}N} }$

structure

In lithium nitride, the lithium atoms form graphite-like hexagonal rings with a nitrogen atom in the center. Further lithium atoms are located above and below the nitrogen nucleus, so that each nitrogen is surrounded by eight lithium nuclei in a hexagonal-bipyramidal geometry.

properties

Physical Properties

Lithium nitride is a fine, red-brown powder with a density of 1.38 g · cm ⁻³ under standard conditions. It melts at 813 ° C and is stable in the absence of moisture and air. Lithium nitride is a good ion conductor.

The enthalpy of formation of lithium nitride is −207 kJ / mol.

Chemical properties

Lithium nitride is a superbase because the N ³⁻ ion has a strongly basic reaction. Lithium nitride hydrolyzes with water to lithium hydroxide and ammonia .

${\displaystyle {\ce {Li3N + 3H2O -> 3LiOH + NH3}}}$

Lithium hydride is formed when heated in a stream of hydrogen . Lithium amide (LiNH ₂ ) and lithium imide (Li ₂ NH) are formed as intermediate stages .

${\displaystyle {\ce {2Li3N +3H2 -> 6LiH + N2 ^}}}$

When lithium nitride is heated with metal chlorides, lithium chloride and the relevant metal nitride are formed.

use

In metallurgy , lithium nitride is used to introduce nitrogen into alloys .

Lithium nitride has also been investigated for hydrogen storage , for example for fuel cells , since it can absorb up to 9.3 % by weight of hydrogen through reaction . Besides arises lithium first lithium imide before finally lithium amide forms. The reaction between lithium imide Li ₂ NH and lithium amide LiNH _{2 is} reversible, which corresponds to a mass fraction of about 7%. However, the necessary temperatures of 255 ° C are still too high for use.

${\displaystyle \mathrm {Li_{3}N\ +\ 2\ H_{2}\ \longrightarrow \ Li_{2}NH\ +\ LiH\ +\ H_{2}\ \rightleftharpoons \ \ LiNH_{2}+\ 2\ LiH} }$

Individual evidence

1. ↑ ^{a b} Structure of Li ₃ N ( Memento from July 19, 2012 in the Internet Archive ).
2. ↑ ^{a b} data sheet lithium nitride from AlfaAesar, accessed on December 15, 2010 ( PDF )(JavaScript required) .
3. ↑ Inorganic Syntheses . John Wiley & Sons, 2009, ISBN 0-470-13288-4 , pp. 53 ( limited preview in Google Book search).
4. ↑ RM Yonco, E. Veleckis, VA Maroni: Solubility of nitrogen in liquid lithium and thermal decomposition of solid Li ₃ N. In: Journal of Nuclear Materials. 57, 1975, p. 317, doi : 10.1016 / 0022-3115 (75) 90216-0 .
5. ↑ ^{a b} Data sheet lithium nitride from Sigma-Aldrich , accessed on April 8, 2011 ( PDF ).
6. ↑ Dominique Laniel, Gunnar Weck, Paul Loubeyre: Direct Reaction of Nitrogen and Lithium up to 75 GPa: Synthesis of the Li3N, LiN, LiN2, and LiN5 Compounds. In: Inorganic Chemistry. 57, 2018, p. 10685, doi : 10.1021 / acs.inorgchem.8b01325 .
7. ^ ^{A b c} A. F. Holleman , E. Wiberg , N. Wiberg : Textbook of Inorganic Chemistry . 101st edition. Walter de Gruyter, Berlin 1995, ISBN 3-11-012641-9 , p. 1153.
8. ^ ^{A b} Albrecht Rabenau: Lithium nitride and related substances, their scientific and practical significance. Sila substitutions . Westdeutscher Verlag GmbH, Opladen 1981, ISBN 978-3-663-01758-5 , p. 12 ( limited preview in Google Book search).
9. ^ Peter Paetzold: Chemistry: An introduction . Walter de Gruyter, Berlin 2009, ISBN 978-3-11-021135-1 , p. 636 ( limited preview in Google Book search).
10. ↑ Hermann Sicius: hydrogen and alkali metals: elements of the first main group . Springer Fachmedien, Wiesbaden 2016, ISBN 978-3-658-12268-3 , p. 23 , doi : 10.1007 / 978-3-658-12268-3 .
11. ^ M. Guntz: Sur l'azoture de lithium. In: Compt. Rend. Hebd. Volume 123, 1896, pp. 995-997 ( digitized on Gallica ).
12. ^ ^{A b} R. Abegg, F. Auerbach, I. Koppel: Handbook of inorganic chemistry . Volume 2, Part 1, Verlag S. Hirzel, 1908, p. 134 ( full text ).
13. ^ KA Hofmann: Textbook of Inorganic Chemistry. 2nd edition, Verlag F. Vieweg & Sohn, 1919, p. 441 ( full text ).
14. ^ DL Perry, SL Phillips: Handbook of Inorganic Compounds: An Electronic Database. CRC Press, 1995, ISBN 978-0-8493-8671-8 , p. 228.
15. ↑ Jan Oliver Löfken: New hydrogen storage made from lithium nitride discovered. In: Image of Science . Retrieved September 8, 2019 . 
16. ↑ New storage medium developed for hydrogen. In: innovations-report.de. November 25, 2002, accessed September 3, 2017 . 
17. ↑ Ping Chen, Zhitao Xiong, Jizhong Luo, Jianyi Lin, Kuang Lee Tan: Interaction of hydrogen with metal nitrides and imides . In: Nature . tape 420 , no. 6913 , October 2002, p. 302-304 , doi : 10.1038 / nature01210 .