Nonmetal nitrides

W. Schnick, Solid state chemistry of nonmetal nitrides. Angew. Chem. Int. Ed. 32 (1993) 806. 

In order to raise the stability of nonmetal nitride network structures the element phosphoms has to be exchanged against silicon. In phosphoms nitrides the relative amount of (N ) never seems to exceed a value of 2/5 and in most examples it is zero. In contrast, in silicon nitrides even all of the nitrogen atoms each may connect three silicon atoms (N ). This topological situation is realized in the two modifications of binary silicon nitride Si3N4 (Fig. 2). 

Peculiarities of Phase and Structure Formation of Metal and Nonmetal Nitrides in Combustion Mode... 

Nitrides — Metal and nonmetal nitrides Lead nitride silver nitride disulfur dinitride pentasulfur hexanitride... 

Schnick W (1993) Solid-state chemistry with nonmetal nitrides. Angew Chem Int Ed Engl 32(6) 806-818... 

The recent development of nonmetal nitride, namely, the graphitic carbon nitride (g-CsN4) materials, has attracted huge attention due to their tunable electronic... 

The crystal stmeture and stoichiometry of these materials is determined from two contributions, geometric and electronic. The geometric factor is an empirical one (8) simple interstitial carbides, nitrides, borides, and hydrides are formed for small ratios of nonmetal to metal radii, eg, < 0.59. 

Whereas finely divided cobalt is pyrophoric, the metal in massive form is not readily attacked by air or water or temperatures below approximately 300°C. Above 300°C, cobalt is oxidized by air. Cobalt combines readily with the halogens to form haUdes and with most of the other nonmetals when heated or in the molten state. Although it does not combine direcdy with nitrogen, cobalt decomposes ammonia at elevated temperatures to form a nitride, and reacts with carbon monoxide above 225°C to form the carbide C02C. Cobalt forms intermetallic compounds with many metals, such as Al, Cr, Mo,... 

All alkali metals react directly with almost all nonmetals except the noble gases. However, only lithium reacts with nitrogen, which it reduces to the nitride ion ... 

As we shall see later, borides (as well as oxides, nitrides, carbides, etc.) react with water to produce a hydrogen compound of the nonmetal. Thus, the reaction of magnesium boride with water might be expected to produce BH3, borane, but instead the product is B2ff6, diborane (m.p. -165.5 °C, b.p. -92.5 °C). This interesting covalent hydride has the structure... 

The "nitrides" of most nonmetals exist. By calling the compounds nitrides, it is indicated that the other element has an electronegativity that is lower than that of nitrogen. Therefore, N02, NF3, N2F2, and the like would not be considered "nitrides" because the other element is the more electronegative. This leaves quite a number of compounds such as HN3, S4N4, (CN)2, that are covalent nitrides. Chemically, these compounds are quite different, and as will be shown later, methods for synthesizing them vary enormously. 

Most reactions of bromine are highly exothermic which can cause incandescence or sudden increase in pressure and rupture of reaction flasks. There are a number of cases of explosions documented in the literature. (NFPA. 1986. Fire Protection Guide on Hazardous Materials, 9th ed. Quincy, MA National Fire Protection Association) Reactions of liquid bromine with most metals (or any metal in finely divided state), metal hydrides, carbonyls and nitrides can be explosive. Many oxides and halides of nonmetals, such as nitrogen triiodide or phosphorus trioxide, react explosively or burst into flame in contact with liquid bromine. 

Vanadium combines with other nonmetals at elevated temperatures forming binary compounds. Such compounds include nitride, VN carbide VC, and the sulfides, VS (or V2S2), V2S3, and V2S5. 

The metal reacts with halogens above 200°C forming its trihalides. It combines with nitrogen above 1,000°C producing a nitride, YN. It combines at elevated temperatures forming binary compounds with most nonmetals and some metalloid elements such as hydrogen, sulfur, carbon, phosphorus, silicon, and selenium. 

In general, the nitrides of most of the metals and many of the nonmetals may be prepared by heating the elements together. Owing to the inactivity of nitrogen at ordinary temperatures, it is usually necessary to heat to a very high temperature. Consequently, the formation of nitrides is often observed in electric furnace work. Magnesium nitride is one of the nitrides easiest to prepare. 

The crystal structure and stoichiometry of these materials is determined from two contributions, geometric and electronic. The geometric factor is an empirical one (8) simple interstitial carbides, nitrides, borides, and hydrides are formed for small ratios of nonmetal to metal radii, eg, rx / rM < 0.59. When this ratio is larger than 0.59, as in the Group 7—10 metals, the structure becomes more complex to compensate for the loss of metal—metal interactions. Although there are minor exceptions, the H gg rule provides a useful basis for predicting structure. 

There is an unusual hetero chain, (SN), discovered in 1910. which did not receive detailed attention until the 1970s. Interest centers on the fact that although it is composed of atoms of two nonmetals, polymeric sulfur nitride (also called polythiazyl) has some physical properties of a metal. The preparation is from tetrasulfur tetranitnde (see page 776) ... 

Why do carbides and nitrides exhibit the properties that make them so useful in industrial applications It is well accepted that these properties are related to the strength of interatomic bonding.2 In transition metal carbides and nitrides, bonding is believed to have both covalent and ionic contributions.3 The carbon or nitrogen atoms occupy interstitial sites in the metal lattice and are believed to promote strong metal-to-nonmetal and metal-to-metal bonds.1 More detailed bonding explanations require... 

The present study made use of diffusion couples where metals were reacted with carbon or nitrogen with the purpose of determining both phase equilibria and nonmetal diffusivities for Group 4 and 5 transition metal carbide and nitride systems. 

---