Chalcogenide group

Table 7.9 Stoichiometries and stmctures of the crystalline chalcogenides of Group 13 elements...

The binary compounds of the Group 13 metals with the elements of Group 15 (N, P, As, Sb, Bi) are stmcturally less diverse than the chalcogenides just considered but they have achieved considerable technological application as III-V semiconductors isoelectronic with Si and Ge (cf. BN isoelectronic with C, p. 207). Their stmctures are summarized in Table 7.10 all adopt the cubic ZnS stmcture except the nitrides of Al, Ga and In which are probably more ionic (less covalent or metallic) than the others. Thallium does not form simple compounds... 

Arsenic, Antimony and Bismuth Table 13.10 Some properties of Group 15 chalcogenides M2X3... 

Of the more complex chalcogenide derivatives of the Group 15 elements two examples must suffiee to indicate the great structural versatility of these elements, particularly... 

The chalcogenides are binary compounds of a chalcogen (i.e., the elements of Group Ilb zinc, cadmium, mercury) with a less electropositive element, such as those of Group VIb (oxygen, sulfur, selenium, and tellurium). This section covers the sulfides, selenides, andtellurides. Oxides are reviewed above in Ch. 11. Most of the chalcogenides have useful optical characteristics and their applications are usually found in optics. 

Fig. 1. Chalcogenide halides in ternary systems having the components the Group IB elements Cu, Ag, and Au, the chalcogens S, Se, and Te, and the halogens Cl, Br, and I, They are indicated as M , Y, and X ", respectively. (Redrawn from A. Rabenau, H. Rau, and G. Rosenstein, J. Less-Common Metals 21, 395 (1970), Fig. 4, p. 401.)...

Chalcogenide Halides of Group IIIB and Lanthanides Bibliography... 

Very little is known about chalcogenide halides of Group IVB elements. Although the existence of sulfide chlorides (45, 274, 329, 365) and of a selenide chloride (329) of titanium was claimed in early publications, their true composition, and even their existence, remains doubtful. They have usually been obtained by the reaction of titanium chlorides with sulfur and selenium, respectively, or with hydrogen sulfide. The synthesis of a pure compound, TiSClj, was published in 1959 (113). It is an intermediate of the reaction of TiCU with HjS. 

Nothing has thus far been reported concerning chalcogenide halides of other elements of Group IVB. 

Although not yet published in a journal, according to thesis work, the vanadium compounds VSCl (11), VSBr, and VSI (208) seem to exist. Numerous niobium chalcogenide halides have been reported, and among these are the best characterized examples of Group VB (see Table X). Only two tantalum compounds, TaSjCU (361) and TaSCls (13) have thus far been described in the literature. 

Just as, in Group VB, niobium, so, in this Group, molybdenum provides most of the examples of the chalcogenide halides. The occurrence and preparation of such compounds are described in numerous publications. In most cases, they have been obtained as powders, with the composition based on chemical analyses only. The presence of defined, homogeneous phases is, therefore, in many cases doubtful. In addition, some published results are contradictory. A decision is possible where a complete structure analysis has been made. As will be shown later, the formation of metal-metal bonds (so-called clusters), as in the case of niobium, is the most characteristic building-principle. Such clusters... 

Only two compounds, W2S7CI8 (362) and W4S9CI6 (97) are mentioned in the older literature, their true nature being uncertain. The existence of the other compounds in Table XV seems to be well established. All of them were reported by the same group, and, with few exceptions, it remains the only work (57, 58, 131). This example illustrates that the lack of information on chalcogenide halides, especially of transition elements, has its main origin in the lack of systematic investigations. 

Again, the complete series of InYX compounds (Y = S,Se,Te X = Cl,Br,I) exists. Of the Group IIIA chalcogenide halides, the indium compounds have been the most extensively studied. 

Group-IIIB-group-IIIB bonds feature in the low-valent chalcogenides of Al, Ga and In shown in Table 1. These involve [Al—Al] ", [Ga—Ga], [In—In] or [In—In—In] in the solid state. The discrete compounds are synthesized by heating stoichiometric mixtures of the metal and S, Se or Te, typically in evacuated quartz... 

Group 6 Metal Chalcogenide Cluster Complexes and Their Relationships to Solid-State Cluster Compounds Taro Saito... 

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