Nitride
Inchemistry,anitrideis achemical compoundofnitrogen.Nitrides can beinorganicororganic,ionicorcovalent.The nitrideanion,N3-ion, is very elusive but compounds of nitride are numerous, although rarely naturally occurring. Some nitrides have a found applications,[1]such aswear-resistantcoatings(e.g.,titanium nitride,TiN), hardceramic materials(e.g.,silicon nitride,Si3N4), andsemiconductors(e.g.,gallium nitride,GaN). The development of GaN-basedlight emitting diodeswas recognized by the 2014Nobel Prize in Physics.[2]Metal nitrido complexesare also common.
Synthesisof inorganic metal nitrides is challenging because nitrogen gas (N2) is not very reactive at low temperatures, but it becomes more reactive at higher temperatures. Therefore, a balance must be achieved between the low reactivity of nitrogen gas at low temperatures and theentropydriven formation of N2at high temperatures.[3]However, synthetic methods for nitrides are growing more sophisticated and the materials are of increasing technological relevance.[4]
Uses of nitrides
[edit]Likecarbides,nitrides are oftenrefractory materialsowing to their highlattice energy,which reflects the strong bonding of "N3−"to metal cation(s). Thus,cubic boron nitride,titanium nitride,andsilicon nitrideare used as cutting materials and hard coatings. Hexagonalboron nitride,which adopts a layered structure, is a useful high-temperature lubricant akin tomolybdenum disulfide.Nitride compounds often have largeband gaps,thus nitrides are usuallyinsulatorsorwide-bandgap semiconductors;examples includeboron nitrideand silicon nitride. The wide-band gap materialgallium nitrideis prized for emitting blue light inLEDs.[5][6]Like some oxides, nitrides can absorb hydrogen and have been discussed in the context ofhydrogen storage,e.g.lithium nitride.
Examples
[edit]Classification of such a varied group of compounds is somewhat arbitrary. Compounds where nitrogen is not assigned −3 oxidation state are not included, such asnitrogen trichloridewhere the oxidation state is +3; nor areammoniaand its many organic derivatives.
Nitrides of the s-block elements
[edit]Only onealkali metalnitride is stable, the purple-reddishlithium nitride(Li3N), which forms when lithium burns in an atmosphere ofN2.[7]Sodium nitrideandpotassium nitridehas been generated, but remains a laboratory curiosity. The nitrides of thealkaline earth metalsthat have the formulaM3N2are however numerous. Examples includeberyllium nitride(Be3N2),magnesium nitride(Mg3N2),calcium nitride(Ca3N2), andstrontium nitride(Sr3N2). The nitrides of electropositive metals (including Li, Zn, and the alkaline earth metals) readily hydrolyze upon contact with water, including the moisture in the air:
- Mg3N2+ 6 H2O → 3 Mg(OH)2+ 2 NH3
Nitrides of the p-block elements
[edit]Boron nitrideexists as several forms (polymorphs). Nitrides ofsiliconand phosphorus are also known, but only the former is commercially important. The nitrides ofaluminium,gallium,andindiumadopt the hexagonalwurtzite structurein which each atom occupies tetrahedral sites. For example, in aluminium nitride, each aluminium atom has four neighboring nitrogen atoms at the corners of a tetrahedron and similarly each nitrogen atom has four neighboring aluminium atoms at the corners of a tetrahedron. This structure is like hexagonal diamond (lonsdaleite) where every carbon atom occupies a tetrahedral site (however wurtzite differs fromsphaleriteanddiamondin the relative orientation of tetrahedra).Thallium(I) nitride(Tl3N) is known, but thallium(III) nitride (TlN) is not.
Transition metal nitrides
[edit]Most metal-rich transition metal nitrides adopt a relatively orderedface-centered cubicorhexagonal close-packedcrystal structure, with octahedral coordination.[8]Sometimes these materials are called "interstitialnitrides ". They are essential for industrialmetallurgy,because they are typically muchharderand lessductilethan their parent metal, and resist air-oxidation.[9]For thegroup 3metals, ScN andYNare both known.Group 4,5,and6transition metals (the titanium, vanadium and chromium groups) all form[10]chemically stable,refractorynitrides with high melting point.Thin filmsoftitanium nitride,zirconium nitride,andtantalum nitrideprotect many industrial surfaces.
Nitrides of thegroup 7and8transition metals tend to be nitrogen-poor, and decompose readily at elevated temperatures. For example,iron nitride,Fe2Ndecomposes at 200 °C. Platinum nitride and osmium nitride may containN2units, and as such should not be called nitrides.[11][12]
Nitrides of heavier members from group11and12are less stable thancopper nitride(Cu3N) andzinc nitride(Zn3N2): drysilver nitride (Ag3N)is acontact explosivewhich may detonate from the slightest touch, even a falling water droplet.[13]
Nitrides of the lanthanides and actinides
[edit]Nitride containing species of the lanthanides and actinides are of scientific interest as they can provide a useful handle for determining covalency of bonding. Nuclear magnetic resonance (NMR) spectroscopy along with quantum chemical analysis has often been used to determine the degree to which metal nitride bonds are ionic or covalent in character. One example, a uranium nitride, has the highest known nitrogen-15 chemical shift.[14]
Molecular nitrides
[edit]
Many metals form molecular nitrido complexes, as discussed in the specialized article. Themain group elementsalso form some molecular nitrides.Cyanogen((CN)2) andtetrasulfur tetranitride(S4N4) are rare examples of a molecular binary (containing one element aside from nitrogen) nitrides. They dissolve in nonpolar solvents. Both undergo polymerization.S4N4is also unstable with respect to the elements, but less so that the isostructuralSe4N4.HeatingS4N4gives a polymer, and a variety of molecular sulfur nitride anions and cations are also known.
Related to but distinct from nitride ispernitridediatomic anion (N2−2) and theazidetriatomic anion (N3-).
References
[edit]- ^Greenwood, Norman N.;Earnshaw, Alan (1997).Chemistry of the Elements(2nd ed.).Butterworth-Heinemann.ISBN978-0-08-037941-8.
- ^"The Nobel Prize in Physics 2014".The Nobel Prize.Nobel Prize Outreach.Retrieved13 January2021.
- ^Sun, Wenhao; Bartel, Christopher J.; Arca, Elisabetta; Bauers, Sage R.; Matthews, Bethany; Orvañanos, Bernardo; Chen, Bor-Rong; Toney, Michael F.; Schelhas, Laura T.; Tumas, William;Tate, Janet;Zakutayev, Andriy; Lany, Stephan; Holder, Aaron M.; Ceder, Gerbrand (2019)."A map of the inorganic ternary metal nitrides".Nature Materials.18(7): 732–739.arXiv:1809.09202.doi:10.1038/s41563-019-0396-2.ISSN1476-4660.PMID31209391.S2CID119461695.
- ^Greenaway, Ann L.; Melamed, Celeste L.; Tellekamp, M. Brooks; Woods-Robinson, Rachel; Toberer, Eric S.; Neilson, James R.; Tamboli, Adele C. (2021-07-26)."Ternary Nitride Materials: Fundamentals and Emerging Device Applications".Annual Review of Materials Research.51(1): 591–618.arXiv:2010.08058.doi:10.1146/annurev-matsci-080819-012444.ISSN1531-7331.S2CID223953608.
- ^Oyama, S. T., ed. (1996).The Chemistry of Transition Metal Carbides and Nitrides.Blackie Academic.ISBN0-7514-0365-2.
- ^Pierson, H. O. (1996).Handbook of refractory carbides and nitrides.William Andrew.ISBN0-8155-1392-5.
- ^Gregory, Duncan H. (2001). "Nitride chemistry of the s-block elements".Coord. Chem. Rev.215:301–345.doi:10.1016/S0010-8545(01)00320-4.
- ^Toth, Louis (2014-04-11).Transition Metal Carbides and Nitrides.Elsevier.ISBN978-0-323-15722-3.
- ^Leineweber, Andreas; Niewa, Rainer; Jacobs, Herbert; Kockelmann, Winfried (2000)."The manganese nitrides η‐Mn3N2 and θ‐Mn6N5 + x: nuclear and magnetic structures".Journal of Materials Chemistry.10(12): 2827–2834.doi:10.1039/b006969h.
- ^Mei, A. B.; Howe, B. M.; Zhang, C.; Sardela, M.; Eckstein, J. N.; Hultman, L.; Rockett, A.; Petrov, I.; Greene, J. E. (2013-10-18)."Physical properties of epitaxial ZrN/MgO(001) layers grown by reactive magnetron sputtering".Journal of Vacuum Science & Technology A.31(6): 061516.Bibcode:2013JVSTA..31f1516M.doi:10.1116/1.4825349.ISSN0734-2101.
- ^Siller, L.; Peltekis, N.; Krishnamurthy, S.; Chao, Y.; Bull, S. J.; Hunt, M. R. C. (2005)."Gold film with gold nitride—A conductor but harder than gold"(PDF).Appl. Phys. Lett.86(22): 221912.Bibcode:2005ApPhL..86v1912S.doi:10.1063/1.1941471.
- ^Montoya, J. A.; Hernández, A. D.; Sanloup, C.; Gregoryanz, E.; Scandolo, S (2007). "OsN2: Crystal structure and electronic properties".Appl. Phys. Lett.90(1): 011909.Bibcode:2007ApPhL..90a1909M.doi:10.1063/1.2430631.
- ^Shanley, Edward S.; Ennis, John L. (1991). "The Chemistry and Free Energy Formation of Silver Nitride".Ind. Eng. Chem. Res.30(11): 2503.doi:10.1021/ie00059a023.
- ^Du, Jingzhen; Seed, John A.; Berryman, Victoria E. J.; Kaltsoyannis, Nikolas; Adams, Ralph W.; Lee, Daniel; Liddle, Stephen T. (2021)."Exceptional uranium(VI)-nitride triple bond covalency from 15N nuclear magnetic resonance spectroscopy and quantum chemical analysis".Nat. Commun.12(1): 5649.Bibcode:2021NatCo..12.5649D.doi:10.1038/s41467-021-25863-2.PMC8463702.PMID34561448.
