Lithium amide

Lithium amide or lithium azanide is an inorganic compound with the chemical formula LiNH₂. It is a white solid with a tetragonal crystal structure.^[1] Lithium amide can be made by treating lithium metal with liquid ammonia:^[2]

2 Li + 2 NH₃ → 2 LiNH₂ + H₂

Lithium amide

__ Li+      __ N3−      __ H+
Names
IUPAC name Lithium amide
Other names Lithium azanide Lithamide
Identifiers
CAS Number	7782-89-0 Y
3D model (JSmol)	Interactive image
ChemSpider	22939 Y
ECHA InfoCard	100.029.062
PubChem CID	24532
UNII	7393OMU9LK Y
CompTox Dashboard (EPA)	DTXSID7064815
InChI InChI=1S/Li.H2N/h;1H2/q+1;-1 Y Key: AFRJJFRNGGLMDW-UHFFFAOYSA-N Y InChI=1/Li.H2N/h;1H2/q+1;-1 Key: AFRJJFRNGGLMDW-UHFFFAOYAO
SMILES [Li+].[NH2-]
Properties
Chemical formula	LiNH2
Molar mass	22.96 g·mol−1
Appearance	white solid
Density	1.178 g/cm3
Melting point	375 °C (707 °F; 648 K)
Boiling point	430 °C (806 °F; 703 K) decomposes
Solubility in water	reacts
Solubility	slightly soluble in ethanol insoluble in ammonia
Thermochemistry
Std enthalpy of formation (ΔfH⦵298)	−182 kJ/mol
Hazards
NFPA 704 (fire diamond)	3 1 2 W
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). N verify (what is YN ?) Infobox references

Lithium amide decomposes into ammonia and lithium imide upon heating.^[3]

Applications

Lithium amide, when mixed with lithium hydride, shows applications in hydrogen storage.^[4][3]The reaction begins with lithium amide's decomposition into ammonia and lithium imide. Lithium hydride then deprotonates ammonia to form lithium amide. The reverse reaction can occur between hydrogen and the lithium imide side product.

Other lithium amides

The conjugate bases of amines are known as amides. Thus, a lithium amide may also refer to any compound in the class of the lithium salt of an amine. These compounds have the general form LiNR₂, with the chemical lithium amide itself as the parent structure. Common lithium amides include lithium diisopropylamide (LDA), lithium tetramethylpiperidide (LiTMP), and lithium hexamethyldisilazide (LiHMDS). They are produced by the reaction of Li metal with the appropriate amine:

2 Li + 2 R₂NH → 2 LiNR₂ + H₂

Lithium amides are very reactive compounds. Specifically, they are strong bases.

Examples

Lithium tetramethylpiperidide has been crystallised as a tetramer.^[5] On the other hand, the lithium derivative of bis(1-phenylethyl)amine crystallises as a trimer:^[6]

Tetrameric lithium tetramethylpiperidide

Trimeric lithium bis(1-phenylethyl)amide

It is also possible to make mixed oligomers of metal alkoxides and amides.^[7] These are related to the superbases, which are mixtures of metal alkoxides and alkyls. The cyclic oligomers form when the nitrogen of the amide forms a sigma bond to a lithium, while the nitrogen lone pair binds to another metal centre.

Other organolithium compounds (such as BuLi) are generally considered to exist in and function via high-order, aggregated species.

See also

• Sodium amide
• Potassium amide
• Butyllithium
• Lithium imide
• Lithium nitride