Inorganic imide

 ( Nitrogen Compounds ) 

The inorganic imide is an inorganic chemical compound containing

• an anion with the chemical formula , in which nitrogen atom is covalently bonded to one hydrogen atom (as in lithium imide and calcium imide ). The other name of that anion is monohydrogen nitride.
• with the chemical formulas or , in which nitrogen atom is also covalently bonded to one hydrogen atom, with two covalent or one covalent double bond from the nitrogen atom to other atoms, respectively (as in heptasulfur imide , sulfur diimide and nitroxyl ).

Imide have the functional groups or as well.

The imides are related to the , containing the anions, the , containing the anions and the or nitride hydrides, containing both nitride and hydride anions.

In addition to solid state imides, molecular imides are also known in dilute gases, where their spectrum can be studied.

When covalently bound to a metal, an imide ligand produces a transition metal imido complex.

When the hydrogen of the imide group is substituted by an organic group, an organoimide results. Complexes of actinide and rare earth elements with organoimides are known.

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Properties Lithium imide undergoes a phase transition at 87 °C where it goes from an ordered to a more symmetric disordered state.

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Structure Many imides have a cubic rock salt structure, with the metal and nitrogen occupying the main positions. The position of the hydrogen atom is hard to determine, but is disordered.

Many of the heavy metal simple imide molecules are linear. This is due to the filled 2p orbital of nitrogen donating electrons to an empty d orbital on the metal.

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Imides in coordination chemistry In coordination chemistry transition metal imido complexes feature the NR^2- ligand. They are similar to oxo ligands in some respects. In some the M-N-C angle is 180º but often the angle is decidedly bent. The parent imide (NH^2-) is an intermediate in nitrogen fixation by synthetic catalysts.Nugent, W. A.; Mayer, J. M., "Metal-Ligand Multiple Bonds," J. Wiley: New York, 1988.

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Formation Heating lithium amide with lithium hydride yields lithium imide and hydrogen gas. This reaction takes place as released ammonia reacts with lithium hydride.

Heating magnesium amide to about 400 °C yields magnesium imide with the loss of ammonia. Magnesium imide itself decomposes if heated between 455 and 490 °C.

Beryllium imide forms from beryllium amide when heated to 230 °C in a vacuum.

When strontium metal is heated with ammonia at 750 °C, the dark yellow strontium imide forms.

When barium vapour is heated with ammonia in an electrical discharge, the gaseous, molecular BaNH is formed. Molecules ScNH, YNH, and LaNH are also known.

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Hydrogen storage

Inorganic imides are of interest because they can reversibly store hydrogen, which may be important for the hydrogen economy. For example, calcium imide can store 2.1% mass of hydrogen. reversibly stores hydrogen and release it at temperatures between 140 and 206 °C. It can reversibly hold 2.3% hydrogen. When hydrogen is added to the imide, amides and hydrides are produced. When imides are heated, they can yield hydridonitrides or nitrides, but these may not easily reabsorb hydrogen.

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List

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Ionic

Lithium imide		cubic	Fm m	a=5.0742
Beryllium imide	BeNH
Magnesium imide	MgNH	hexagonal	P6/ m	a = 11.567 Å c = 3.683Å Z=12
Dilithium magnesium imide
Disilicon dinitride imide
		amourphous
		amourphous
		amourphous
potassium imido nitrido silicate		cubic	P4332	a = 10.789
Calcium imide	CaNH	hexagonal	Fm3 m
Dilithium calcium imide		hexagonal
Magnesium calcium diimide		cubic
Lithium calcium magnesium imide
Strontium imide	SrNH	orthorhombic	Pmna	a =7.5770 b =3.92260 c =5.69652 Z=4
Tin(IV) diamide imide
Barium imide	BaNH	tetragonal	I4/ mmm	a=4.062 c=6.072 Z=2
Lanthanum imide		rock salt		a=5.32
Cerium(II) imide	CeNH
Ytterbium(II) imide	YbNH	cubic		a=4.85
		cubic	P4132	a = 10.304, Z = 4
Thorium(IV) dinitride imide		hexagonal	P3 m	a = 3.886 c = 6.185 Å

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Molecular

Boron imide		polymer
	HNO	bent		14332-28-6
Aluminium amide imide		polymer
Silicon dimide
	HNS	bent		14616-59-2
Sulfur diimide
Heptasulfur imide				293-42-5
				1003-75-4
				1003-76-5
				638-50-6
Scandium(II) imide	ScNH
Gallium(III) imide		polymer
Yttrium(II) imide	YNH
Barium imide	BaNH	linear
Lanthanum(II) imide	LaNH	linear	C∞v
Cerium(II) imide	CeNH	linear	C∞v
Uranimine nitride
Uranimine dihydride

Molecular imines of other actinides called neptunimine and plutonimine have been postulated to exist in the gas phase or noble gas matrix.

Categories: Nitrogen Compounds, Hydrogen Compounds

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