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| Names | |
|---|---|
| IUPAC name Lithium amide | |
| Other names Lithium azanide Lithamide | |
| Identifiers | |
3D model (JSmol) | |
| ChemSpider |
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| ECHA InfoCard | 100.029.062 |
| UNII | |
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| Properties | |
| 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 |
| reacts | |
| Solubility | slightly soluble inethanol insoluble inammonia |
| Thermochemistry | |
Std enthalpy of formation(ΔfH⦵298) | −182 kJ/mol |
| Hazards | |
| NFPA 704 (fire diamond) | |
Except where otherwise noted, data are given for materials in theirstandard state (at 25 °C [77 °F], 100 kPa). | |
Lithium amide orlithium azanide is aninorganic compound with the chemical formulaLiNH2. It is a white solid with a tetragonal crystal structure.[1] Lithium amide can be made by treatinglithium metal with liquidammonia:[2]
Lithium amide decomposes intoammonia andlithium imide upon heating.[3]
Lithium amide, when mixed withlithium hydride, shows applications inhydrogen storage.[4][3]The reaction begins with lithium amide's decomposition intoammonia andlithium imide. Lithium hydride thendeprotonates ammonia to form lithium amide. The reverse reaction can occur between hydrogen and the lithium imide side product.
The conjugate bases of amines are known as amides. Thus, alithium amide may also refer to any compound in the class of the lithium salt of anamine. These compounds have the general formLiNR2, with the chemical lithium amide itself as theparent structure. Common lithium amides includelithium diisopropylamide (LDA),lithium tetramethylpiperidide (LiTMP), andlithium hexamethyldisilazide (LiHMDS). They are produced by the reaction of Li metal with the appropriate amine:
Lithium amides are very reactive compounds. Specifically, they are strongbases.
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]
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It is also possible to make mixed oligomers of metalalkoxides and amides.[7] These are related to thesuperbases, which are mixtures of metal alkoxides and alkyls. The cyclic oligomers form when the nitrogen of the amide forms asigma bond to a lithium, while the nitrogenlone pair binds to another metal centre.
Other organolithium compounds (such asBuLi) are generally considered to exist in and function via high-order, aggregated species.
