Binary compounds and salts

There are good overviews of zinc chemistry in several inorganic textbooks, especially those by Greenwood and Eamshaw " and by Cotton, Wilkinson, and their recent collaborators. Much detailed information, especially on the preparation and properties of binary compounds and salts, can be found in the elderly multivolume treatises of Mellor and Pascal, while Sidgwick s more modest pair of volumes also contains much useful information of this type. The organometallic chemistry of zinc is considered in detail elsewhere (see Zinc Organometallic Chemistry). 

The Reactions section highlights only important reactions that include formation of binary compounds, oxo salts, and complexes. 

An existence of immiscibility region in any binary subsystem leads to an appearance of immiscibility phenomena in ternary mixtures and the second critical surfaces with the equilibrium Li = L2. The available experimental data on ternary aqueous systems with volatile (inorganic gas or organic compound) and salt component show the influence of added salts on the mutual miscibility of water and the volatile component. 

Carbides, which are binary compounds containing anionic carbon, occur as covalent and as salt-like compounds. The salt-like carbides are water-reactive and, upon hydrolysis, yield flammable hydrocarbons. Typical hydrolysis reactions include ... 

Other oxoacid salts and binary compounds are more conveniently discussed under the chemistry of the appropriate non-metals in later chapters. 

Nitrogen forms binary compounds with almost all elements of the periodic table and for many elements several stoichiometries are observed, e.g. MnN, Mn Ns, Mn3N2, MniN, Mn4N and Mn tN (9.2 < jc < 25.3). Nitrides are frequently classified into 4 groups salt-like , covalent, diamond-like and metallic (or interstitial ). The remarks on p. 64 concerning the limitations of such classifications are relevant here. The two main methods of preparation are by direct reaction of the metal with Ni or NH3 (often at high temperatures) and the thermal decomposition of metal amides, e.g. ... 

Although not strictly binary compounds, hydroxides are conveniently classified here between hydrated salts, since both release water on heating and incorporate certain common features of behaviour, and oxides, which are the usual residual product. A number of hydroxide decomposition studies have extended measurements to consider the relationship with subsequent higher temperature changes in the product oxide. 

Low-temperature solvents are not readily available for many refractory compounds and semiconductors of interest. Molten salt electrolysis is utilized in many instances, as for the synthesis and deposition of elemental materials such as Al, Si, and also a wide variety of binary and ternary compounds such as borides, carbides, silicides, phosphides, arsenides, and sulfides, and the semiconductors SiC, GaAs, and GaP and InP [16], A few available reports regarding the metal chalcogenides examined in this chapter will be addressed in the respective sections. Let us note here that halide fluxes provide a good reaction medium for the crystal growth of refractory compounds. A wide spectrum of alkali and alkaline earth halides provides... 

Arsenides, antimonides and bismuthides. A number of salt-like related binary compounds formed with these semi-metals pertain to the following structure types NaCl, NiAs, ZnS, Na3As, FeS2, etc. 

Selenides, tellurides andpolonides. Se, Te and Po react easily with most metals and non-metals to form binary compounds (selenides and tellurides are common mineral forms of these elements). Non-stoichiometry is frequently observed in the compounds with the transition elements many of these compounds may be described as metallic alloys. The compounds of the metals of the first two groups may be considered the salts of the acids H2Se, H2Te, etc. The alkali metal selenides... 

Lanthanum combines with nitrogen, carbon, sulfur and phosphorus at elevated temperatures, forming binary salts. Also, with metalloid elements such as boron, silicon, selenium, and arsenic, similar reactions occur at high temperatures forming similar binary compounds. 

Thallium(I) sulfide, selenide and telluride are all well-established compounds, and in the case of all three elements, binary compounds other than M1 and Mln species and double sulfides are also known, as are Tl salts of trithiocarbonate, azidothiocarbonate, etc.1... 

Double Decomposition.—Many binary compounds may be regarded as salts of definite binary acids as well as compounds formed by the union of two elements. Among such compounds are the metallic halides, sulfides, selenides, tellurides, and peroxides. Many salts of these acids may be made by neutralizing a soluble base with the appropriate acid a much larger number may be made by the method of double decomposition (Exercise 15). 

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