Chromium nitrides

Chromium nitride (CrN) is an interstitial compound, with nitrogen atoms occupying the octahedral holes in the chromium lattice [231] as such, it is not strictly a Cr(III) compound, nor does it contain nitride ions (N ). Chromium forms a second interstitial nitride, dichromium nitride, Cr2N. 

Among the transition metal nitrides, cubic CrN has been identified as a better coating and superhard material due to its hardness, excellent corrosion, oxidation 

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Nitrogen can dissolve at elevated temperatures and precipitate as chromium nitrids at lower temperatures with similar effects to those described in the previous section, although there are some differences in detail. 

Chromium iron manganese brown spinel, formula and DCMA number, 7 348t Chromium iron nickel black spinel, formula and DCMA number, 7 348t Chromium isotopes, 6 476 Chromium magnesium oxide, 5 583 Chromium manganese zinc brown spinel, formula and DCMA number, 7 348t Chromium-nickel alloys, 77 100-101 Chromium-nickel-iron alloys, 17 102-103 Chromium-nickel stainless steels, 15 563 Chromium niobium titanium buff rutile, formula and DCMA number, 7 347t Chromium(III) nitrate, 6 533 Chromium nitride, 4 668... 

C produces chromium nitride, CrN. Reaction with nitric oxide forms chromium nitride and chromium oxide. 

Test how chromium nitride reacts with water and with an alkali solution in the cold and with heating. Roast part of the nitride in a porcelain crucible on the flame of a burner. Identify the product. 

For sulphur nitride, see nitrogen sulphide for selenium, nitride, see nitrogen selenide and for tellurium nitride, see nitrogen telluride. J. von Liebig 26 obtained a brown powder by igniting chromium chloride in ammonia, and he thought the product was elemental chromium. A. Schrotter showed that the product is chromium nitride, Cr2N2 or CrN. 

See Potassium nitrate Chromium nitride See other NITRIDES ... 

The stability of the chromium nitride triple bond makes it possible to subject preformed CrVI nitrides to reductive conditions that produce the corresponding Crv nitride. A recent example of this process was reported in which treatment of 40 with Na/Hg afforded nitride 41. X-ray crystallographic analysis revealed a dimeric complex with M2(p-N)2 core (Eq. (12)) [20]. 

As discussed above, the ligands that have been typically utilized for the preparation of chromium nitrides are multidentate. Consequently, ligand exchange reactions of such complexes are difficult and rare. Wieghardt and co-workers have reported such a process, however, for the synthesis of a nitrido chromium cyanide complex 43 (Eq. (13)) [18]. Thus, treatment of CrN(salen) 42 with excess sodium cyanide and tetramethyl ammonium chloride results in the formation of a six-coordinate penta-cyano chromium nitride [21]. 

Cummins has reported that treatment of CrVI complex 47 with 48 at elevated temperature affords the corresponding nitride 49 (Eq. (15)) [23]. This method offers a useful alternative to the other existing methodologies for the preparation of chromium nitrides. The thermodynamic stability of anthracene contributes significantly to the driving force for this process. Cummins has also reported the preparation of chromium nitride 51 from NO and a Cr111 triamide 50, and (THF)2V(Mes)3 (Eq. (16)) [24],... 

Ligand exchange reactions of monodentate amides, iodides, or alkoxide complexes with other amides, alkoxides as well as sulfides, and carbon ligands has been documented [23,25]. A rather unique reaction of a trimethylsilylmethyl ligand bound to a chromium nitride has been reported thus, reaction of tert-butyl isocyanide with 52 is reported to furnish 53 (Eq. (17)). 

Chromium nitrides have been prepared by several routes heating of chromium metal in N2, reaction of chromium borides with NH3, and heating of CrCly in gaseous NH3. The two stable nitrides have the composition Cr2N and CrN see Nitrides Transition Metal Solid-state Chemistry). At very high temperatures, both decompose into the constituent elements (CrN, > 1425 °C CryN, >700 °C). CrN is very stable chemically, while CryN dissolves in dilute acid with liberation OfH2. 

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