Magnesium nitride, which possesses the

chemical formula A chemical formula is a way of presenting information about the chemical proportions of atoms that constitute a particular chemical compound or molecule, using chemical element symbols, numbers, and sometimes also other symbols, such as pare ...

, is an

inorganic compound An inorganic compound is typically a chemical compound that lacks carbon–hydrogen bonds⁠that is, a compound that is not an organic compound. The study of inorganic compounds is a subfield of chemistry known as ''inorganic chemistry''. Inorgan ...

magnesium Magnesium is a chemical element; it has Symbol (chemistry), symbol Mg and atomic number 12. It is a shiny gray metal having a low density, low melting point and high chemical reactivity. Like the other alkaline earth metals (group 2 ...

and

nitrogen Nitrogen is a chemical element; it has Symbol (chemistry), symbol N and atomic number 7. Nitrogen is a Nonmetal (chemistry), nonmetal and the lightest member of pnictogen, group 15 of the periodic table, often called the Pnictogen, pnictogens. ...

. At room temperature and pressure it is a greenish yellow powder.

History

When measuring the boiling point of magnesium, Henri Étienne Sainte-Claire Deville and Henri Caron identified that molten magnesium they distilled covered itself by "small colorless and transparent needles which are destroyed fairly quickly by transforming into ammonia and magnesia". In their 1857 publication the chemists interpreted it as a likely nitride similar to those discovered by Friedrich Wöhler and Heinrich Rose. It was indeed confirmed in 1862 when Friedrich Briegleb and Johann Georg Anton Geuther synthesized the compound on purpose and first studied it.

Preparation

* By passing dry, very pure nitrogen over heated magnesium at for 90 minutes: : * By passing dry

ammonia Ammonia is an inorganic chemical compound of nitrogen and hydrogen with the chemical formula, formula . A Binary compounds of hydrogen, stable binary hydride and the simplest pnictogen hydride, ammonia is a colourless gas with a distinctive pu ...

over heated magnesium at for 4 hours: : This second method is preferred despite the additional time required due to the difficulty of fully purifying nitrogen gas to prevent the formation of unwanted oxides.

Chemistry

Magnesium nitride reacts with water to produce

magnesium hydroxide Magnesium hydroxide is an inorganic compound with the chemical formula Mg(OH)2. It occurs in nature as the mineral brucite. It is a white solid with low solubility in water (). Magnesium hydroxide is a common component of antacids, such as milk o ...

and

gas, as do many metal nitrides. : In fact, when magnesium is burned in air, some magnesium nitride is formed in addition to the principal product,

magnesium oxide Magnesium oxide (MgO), or magnesia, is a white hygroscopic solid mineral that occurs naturally as periclase and is a source of magnesium (see also oxide). It has an empirical formula of MgO and consists of a lattice of Mg2+ ions and O2− ions ...

. 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. These include the and solids which both become thermodynamically stable near 50 GPa. The is composed of exotic ''cis''-tetranitrogen species with N-N bond orders close to one. This compound was recovered to ambient conditions, along with the units, marking only the fourth polynitrogen entity bulk stabilized at ambient conditions.

Uses and history

When isolating

argon Argon is a chemical element; it has symbol Ar and atomic number 18. It is in group 18 of the periodic table and is a noble gas. Argon is the third most abundant gas in Earth's atmosphere, at 0.934% (9340 ppmv). It is more than twice as abu ...

, William Ramsay passed dry air over

copper Copper is a chemical element; it has symbol Cu (from Latin ) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pinkish-orang ...

to remove

oxygen Oxygen is a chemical element; it has chemical symbol, symbol O and atomic number 8. It is a member of the chalcogen group (periodic table), group in the periodic table, a highly reactivity (chemistry), reactive nonmetal (chemistry), non ...

and over

to remove the

, forming magnesium nitride. Magnesium nitride was the

catalyst Catalysis () is the increase in rate of a chemical reaction due to an added substance known as a catalyst (). Catalysts are not consumed by the reaction and remain unchanged after it. If the reaction is rapid and the catalyst recycles quick ...

in the first practical synthesis of borazon (cubic boron nitride). 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 Diamond is a Allotropes of carbon, solid form of the element carbon with its atoms arranged in a crystal structure called diamond cubic. Diamond is tasteless, odourless, strong, brittle solid, colourless in pure form, a poor conductor of e ...

), but with no success. Out of desperation and curiosity (he called it the "make the maximum number of mistakes" approach), 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. Magnesium nitride has also been applied to synthesize aluminum nitride nanocrystals, cubic boron nitride and nitrides of aluminum and Group 3 It has also been proposed as an intermediate in a fossil-fuel-free nitrogen fixation process.

History

Preparation

Chemistry

Uses and history

References

Further reading