nitride n : a compound containing nitrogen and a more electropositive element (such as phosphorus or a metal)
- Italian: nitruro
In chemistry a nitride is a compound of nitrogen with a less electronegative element where nitrogen has an oxidation state of -3. Note that there are exceptions to this naming convention, the nitrides of hydrogen, NH3 and carbon, (CN)2, are called ammonia and cyanogen respectively and that the nitrides of bromine, iodine are called nitrogen tribromide and nitrogen triiodide. Note that nitrogen also forms pernitrides, that contain N22− and azides, that contain N3−.
Nitrogen has one of the highest electronegativities, only oxygen, fluorine and chlorine (in Paulling & Mulliken scales) are higher. This means that the nitrides are a very large group of compounds. They have wide range of properties and applications.
- refractory materials e.g.
- lubricant e.g. hexagonal boron nitride, BN
- cutting materials e.g. silicon nitride, Si3N4
- insulators e.g. boron nitride, BN, silicon nitride, Si3N4
- semiconductors e.g. gallium nitride, GaN
- metal coatings e.g. titanium nitride, TiN
- hydrogen storage e.g Lithium nitride, Li3N
- salt like, e.g. lithium nitride, Li3N, beryllium nitride, Be3N2
- interstitial e.g. titanium nitride, TiN
- intermediate e.g. iron nitride, Fe2N
Nitride ionThe nitride ion is N3− (a nitrogen atom plus three electrons). The extra electrons give the nitrogen atom a closed inert gas shell. The nitride ion is isoelectronic with the oxide anion, O2−, and the fluoride anion, F− and has an ionic radius estimated to be 140 pm. The nitride ion is a strong π-donor ligand, stronger than O2−. It forms nitrido complexes which have a short metal nitrogen bond length indicating multiple bonding.
Salt like nitridesThe salt like nitrides are formed by:
- the alkaline earth metals Mg3N2, Be3N2 and Ca3N2
- the group 3 metals e.g. scandium nitride, ScN
- the group 11 metals e.g. copper nitride, Cu3N
- the group 12 metals e.g. Zn3N2
Covalent nitrides:These include, boron nitride silicon and phosphorus.
- The diamond like nitrides of aluminium,
and indium all
have the wurtzite
structure in which each atom occupies tetrahedral sites. For
example in aluminium nitride, each aluminium atom has four
neighbouring nitrogen atoms at the corners of a tetrahedron and
similarly each nitrogen atom has four neighbouring aluminium atoms
at the corners of a tetrahedron. This structure is like hexagonal
diamond (Lonsdaleite) where every carbon atom occupies a
tetrahedral site (however wurzite differs from sphalerite and diamond in the relative
orientation of tetrahedra) Note that thallium(III) nitride, TlN is
not known, whereas thallium(I) nitride, Tl3N is.
- These include cyanogen, (CN)2 and S2N2 and tetrasulfur tetranitride, S4N4. (Note that sulfur forms another nitride which is polymeric, (SN)x, this is a metallic conductor and has been called a one-dimensional metal.)
Interstitial nitridesThe interstitial nitrides are formed by transition metals where there is a sufficient difference in size between the metal atom and the nitrogen to allow the host metal lattice to accommodate the nitrogen atom. This condition is true for the group 4, 5 and 6 transition metals i.e. the Titanium, Vanadium and Chromium groups. The group 4 and 5 nitrides are refractory i.e. high melting and chemically stable.
Intermediate nitridesGroup 7 and 8 transition metals form nitrides that decompose readily e.g iron nitride, Fe2N melts with decomposition at 200oC. The precious metals are currently being investigated by a number of researchers and thin films of platinum, gold and osmium nitrides have been produced. However there is some discussion as to their structures and their properties. Platinum nitride and osmium nitride for example are now believed to contain N2 units and as such should not be called nitrides.
- H.O Pierson (1996). Handbook of refractory carbides and nitrides, William Andrew Inc. ISBN 0-8155-1392-5
nitride in German: Nitride
nitride in Estonian: Nitriidid
nitride in Spanish: Nitruro
nitride in French: Nitrure
nitride in Dutch: Nitride
nitride in Polish: Azotki
nitride in Portuguese: Nitreto
nitride in Russian: Нитриды
nitride in Finnish: Nitridi
nitride in Ukrainian: Нітриди
nitride in Chinese: 氮化物