Magnesium nitride

Magnesium nitride
Names
	IUPAC name Magnesium nitride
Identifiers
CAS Number	12057-71-5 ;
3D model (JSmol)	Interactive image;
ECHA InfoCard	100.031.826
PubChem CID	16212682;
UNII	7941Y31SR6 ;
CompTox Dashboard (EPA)	DTXSID701014275 ;
	SMILES [Mg+2].[Mg+2].[Mg+2].[N-3].[N-3];
Properties
Chemical formula	Mg3N2
Molar mass	100.9494 g/mol
Appearance	greenish yellow powder
Density	2.712 g/cm3
Melting point	approx. 1500°C
Hazards
Safety data sheet	External MSDS
R-phrases (outdated)	R36, R37, R38
S-phrases (outdated)	S26, S36
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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	Infobox references

Magnesium nitride, which possesses the chemical formula Mg₃N₂, is an inorganic compound of magnesium and nitrogen. At room temperature and pressure it is a greenish yellow powder.

Preparation

By passing dry nitrogen over heated magnesium:

{\begin{matrix}{}\\{\ce {{3Mg}+N2->[{\ce {800^{\circ }C}}]Mg3N2}}\\{}\end{matrix}}

or ammonia:

{\begin{matrix}{}\\{\ce {{3Mg}+2NH3->[{\ce {700^{\circ }C}}]{Mg3N2}+3H2}}\\{}\end{matrix}}

Chemistry

Magnesium nitride reacts with water to produce magnesium hydroxide and ammonia gas, as do many metal nitrides.

Mg₃N_2(s) + 6 H₂O_(l) → 3 Mg(OH)_2(aq) + 2 NH_3(g)

In fact, when magnesium is burned in air, some magnesium nitride is formed in addition to the principal product, magnesium oxide.

Thermal decomposition of magnesium nitride gives magnesium and nitrogen gas (at 700-1500 °C).

At high pressures, the stability and formation of new nitrogen-rich nitrides (N/Mg ratio equal or greater to one) were suggested and later discovered.[1][2][3] These include the Mg₂N₄ and MgN₄ solids which both become thermodynamically stable near 50 GPa.[4] The Mg₂N₄ is composed of exotic cis-tetranitrogen N₄⁴⁻ species with N-N bond orders close to one. This Mg₂N₄ compound was recovered to ambient conditions, along with the N₄⁴⁻ units, marking only the fourth polynitrogen entitiy bulk stabilized at ambient conditions.

Uses

Magnesium nitride was the catalyst in the first practical synthesis of borazon (cubic boron nitride).[5]

Robert H. Wentorf, Jr. was trying to convert the hexagonal form of boron nitride into the cubic form by a combination of heat, pressure, and a catalyst. He had already tried all the logical catalysts (for instance, those that catalyze the synthesis of diamond), but with no success.

Out of desperation and curiosity (he called it the "make the maximum number of mistakes" approach[6]), he added some magnesium wire to the hexagonal boron nitride and gave it the same pressure and heat treatment. When he examined the wire under a microscope, he found tiny dark lumps clinging to it. These lumps could scratch a polished block of boron carbide, something only diamond was known to do.

From the smell of ammonia, caused by the reaction of magnesium nitride with the moisture in the air, he deduced that the magnesium metal had reacted with the boron nitride to form magnesium nitride, which was the true catalyst.

When isolating argon, William Ramsay passed dry air over copper to remove oxygen and over magnesium to remove the nitrogen, forming magnesium nitride.

References

Yu, Shuyin; Huang, Bowen; Zeng, Qingfeng; Oganov, Artem R.; Zhang, Litong; Frapper, Gilles (June 2017). "Emergence of Novel Polynitrogen Molecule-like Species, Covalent Chains, and Layers in Magnesium–Nitrogen Mg x N y Phases under High Pressure". The Journal of Physical Chemistry C. 121 (21): 11037–11046. doi:10.1021/acs.jpcc.7b00474. ISSN 1932-7447.
Wei, Shuli; Li, Da; Liu, Zhao; Li, Xin; Tian, Fubo; Duan, Defang; Liu, Bingbing; Cui, Tian (2017). "Alkaline-earth metal (Mg) polynitrides at high pressure as possible high-energy materials". Physical Chemistry Chemical Physics. 19 (13): 9246–9252. doi:10.1039/C6CP08771J. ISSN 1463-9076. PMID 28322368.
Xia, Kang; Zheng, Xianxu; Yuan, Jianan; Liu, Cong; Gao, Hao; Wu, Qiang; Sun, Jian (2019-04-25). "Pressure-Stabilized High-Energy-Density Alkaline-Earth-Metal Pentazolate Salts". The Journal of Physical Chemistry C. 123 (16): 10205–10211. doi:10.1021/acs.jpcc.8b12527. ISSN 1932-7447.
Laniel, Dominique; Winkler, Bjoern; Koemets, Egor; Fedotenko, Timofey; Bykov, Maxim; Bykova, Elena; Dubrovinsky, Leonid; Dubrovinskaia, Natalia (December 2019). "Synthesis of magnesium-nitrogen salts of polynitrogen anions". Nature Communications. 10 (1): 4515. doi:10.1038/s41467-019-12530-w. ISSN 2041-1723. PMC 6778147. PMID 31586062.
R. H. Wentorf, Jr. (March 1961). "Synthesis of the Cubic Form of Boron Nitride". Journal of Chemical Physics. 34 (3): 809–812. doi:10.1063/1.1731679.
Robert H. Wentorf, Jr. (October 1993). "Discovering a Material That's Harder Than Diamond". R&D Innovator. Retrieved June 28, 2006.

Magnesium nitride

Preparation

Chemistry

Uses

References

Further reading