Lithium nitride is a compound with the formula Li3N. It is the only stable alkali metal nitride. The solid is a red or purple color and has a high melting point.
Preparation and handling 
Lithium nitride is prepared by direct combination of elemental lithium with nitrogen gas:
- 6 Li + N2 → 2 Li3N
Instead of burning lithium metal in an atmosphere of nitrogen, a solution of lithium in liquid sodium metal can be treated with N2. Lithium nitride reacts violently with water to produce ammonia:
- Li3N + 3 H2O → 3 LiOH + NH3
Li3N has an unusual crystal structure that consists of two types of layers, one sheet has the composition Li2N− contains 6-coordinate Li centers and the other sheet consists only of lithium cations.
The hypothetical nitride ion, N3−, would be an extremely strong Brønsted base, easily qualifying as a superbase. It is, in fact, a stronger base than the hydride ion, and so deprotonates hydrogen:
- Li3N + 2 H2 → LiNH2 + 2 LiH
Lithium nitride has been investigated as a storage medium for hydrogen gas, as the reaction is reversible at 270 °C. Up to 11.5% by weight absorption of hydrogen has been achieved.
- ^ Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth–Heinemann. ISBN 0080379419.
- ^ E. Döneges "Lithium Nitride" in Handbook of Preparative Inorganic Chemistry, 2nd Ed. Edited by G. Brauer, Academic Press, 1963, NY. Vol. 1. p. 984.
- ^ Barker M.G., Blake A.J, Edwards P.P., Gregory D.H., Hamor T. A., Siddons D. J., Smith S. E. (1999). "Novel layered lithium nitridonickelates; effect of Li vacancy concentration on N co-ordination geometry and Ni oxidation state". Chem. Commun. (13): 1187–1188. doi:10.1039/a902962a.
- ^ Ping Chen, Zhitao Xiong, Jizhong Luo, Jianyi Lin and Kuang Lee Tan (2002). "Interaction of hydrogen with metal nitrides and amides". Nature 420 (6913): 302–304. doi:10.1038/nature01210. PMID 12447436.
See also