Nitrides and Phosphides

The alkali metals and alkaline earth metals are reactive toward most nonmetallic elements. Accordingly, they react with nitrogen, phosphorus, and arsenic to give binary compounds, but only those of nitrogen and phosphorus will be considered here. The reactions occur when the two elements are heated together as shown in the following equations  

Although the products are written as simple ionic binary compounds, it is known that complex materials containing anions that consist of polyhedral species containing the nonmetal are also produced. For example, a P73- cluster is known, which has six of the phosphorus atoms arranged in a trigonal prism with the seventh occupying a position above the triangular face on one end of the prism. 

The nitrides and phosphides of the Group IA and IIA metals contain anions of high charge, which behave as strong bases. Therefore, they abstract protons from a variety of proton donors. The following reactions are typical  

The nitrides and phosphides of the Group IA and IIA metals are not of great commercial importance. 

Vorob ev, Yu, A. Raikov, and O. G. Polyachenok, Vestnik Akad. Nauk Belarus. 

Obolonchik and L. M. Prokoshina, Zhur. priklad. Khim. (Leningrad), 1971.44, 2166. 

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The extension of this approach to artificial leaves based on titanates, niobates, tantalates, metal nitrides and phosphides, metal sulfides, and other transition metal oxides appears possible and useful in order to enhance the photocatalytic efficiency. In addition, the construction of multicomponent systems such as Ti02-CdS or MoS2-CdSe for overall water splitting could also lead to further improvements. This... 

Most nonmetallic elements will react with the group IA and IIA metals to give binary compounds. Heating the metals with nitrogen or phosphorus gives nitrides and phosphides of the metals. 

In the last decade, numerous compounds of these types have been the subject of detailed CVD studies, demonstrating their potential for the deposition of the corresponding binary materials. Most of the work has concentrated on binary nitrides and phosphides, while the deposition of binary MSb films has been studied to a far lesser extent. The lack of potential precursors has been the major problem for the deposition of group 13-antimonide films for many years. Only a very few group 13-Sb compounds have been known until we and Wells established general synthetic pathways as was shown in Sections 2 and 3. Consequently, detailed investigations concerning their potential to serve for the deposition of the desired materials... 

The chlorides, bromides, iodides, and cyanides are generally vigorously attacked by fluorine in the cold sulphides, nitrides, and phosphides are attacked in the cold or may be when warmed a little the oxides of the alkalies and alkaline earths are vigorously attacked with incandescence the other oxides usually require to be warmed. The sulphates usually require warming the nitrates generally resist attack even when warmed. The phosphates are more easily attacked than the sulphates. The carbonates of sodium, lithium, calcium, and lead are decomposed at ordinary temp, with incandescence, but potassium carbonate is not decomposed even at a dull red heat. Fluorine does not act on sodium bofate. Most of these reactions have been qualitatively studied by H. Moissan,15 and described in his monograph, Lefluor et ses composes (Paris, 1900). 

The difference in heat of formation is even more marked between the nitrides and phosphides. By the same reasoning as for the oxides and sulphides, the alkali phosphides (where r+ is large) should have higher heats of formation than nitrides while the nitrides, with the exception of Li3N, cannot be prepared, the phosphides and arsenides of the alkali metals are fairly stable compounds. 

The Nitrides and Phosphides, Arsenides and Antimonides—Complex Amines and their Salts—Acid Amides—The Cyanides and the Double Cyanides. 

C. C. Cummins, Terminal, Anionic Carbide, Nitride, and Phosphide Transition-Metal Complexes as Synthetic Entries to Low-Coordinate Phosphorus Derivatives, Angew. Chem. Int. Ed. 45, 862-870 (2006). 

Synthesis ofSi3N4, P3N5, Metal Nitrides and Phosphides... 

For the above reasons nitrogen forms many compounds of types not formed by other elements of this group, and for this reason we deal separately with the stereochemistry of this element. For example, the only compounds of N and P which are structurally similar are the molecules in which the elements are 3-covalent and the phosphonium and ammonium ions. There are no nitrogen analogues of the phosphorus pentahalides, and there is little resemblance between the oxygen compounds of the two elements. Monatomic ions of nitrogen and phosphorus are known only in the solid state, in the salt-like nitrides and phosphides of the more electropositive elements. The multiple-bonded azide ion, N3, is peculiar to nitrogen. 

Interstitial structures are not possible for the larger P and As atoms, and apart from a few cases such as LaP, PrP, and GeP with the NaCl structure there is usually little similarity between nitrides and phosphides (or arsenides). Compare, for example, the formulae of the nitrides and phosphides of Mo and W M02N, W2N, MoN, and WN, but M03P, W3P, MoP, WP, M0P2, and... 

Nitrides and Phosphides. The passage of a high-frequency discharge through the mixture VCl4(g)-H2-N2 affords cubic VN0.95. The valence-band spectrum of VN has been analysed. Single crystals of VP2 have been obtained by chemical transport it has the NbAs type structure, whereas the high-pressure phase VP, 75 has a PbFCl type structure. ... 

The nitrides (and phosphides) of many of the transition metals form crystals with the sodium chloride structure. This description, however, must not be interpreted as implying that they are ionic in character, for in fact they display many of the properties of intermetallic systems. For this reason a discussion of these nitrides is deferred to chapter 13. 

Many carbides and silicides of composition AX are formed by transition metals. These carbides and silicides are characterized by very high melting points, extreme hardness, optical opacity and relatively high electrical conductivity. Many of them have the sodium chloride structure but they are not ionic compounds rather do they resemble the corresponding nitrides and phosphides in simulating alloy systems in many of their properties. For this reason they will be discussed later. 

Most of the studies on catalytic activity of the 1st, 2nd and 3rd TMS supported on carbon have been using various model compounds, although to a lesser extent real feeds have also been included in the studies. In this case, the Fe supported on AC have attracted some attention. In recent years, the carbon-supported metal carbides, nitrides and phosphides were also tested as catalysts for hydroprocessing reactions. 

Thermodynamic Data on Alloys , by Kubaschewski and Catterall, critically surveys data on some 400 binary and ternary metallic systems, with the term alloy interpreted to include transition-metal oxides, sulphides, carbides, nitrides, and phosphides. When available, values are given for the integral enthalpy and entropy of formation of the alloy, the relative partial molar enthalpy and entropy of one component, and the volume change on mixing. 

Although the energy gaps are not known for most members of the following group of nitrides and phosphides one is tempted to deduce nonmetallic properties at least for LuN ... 

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