Tellurium complexes properties

Tellurium Selenides. TeUurium selenides or selenium teUurides are unknown. The molten elements are miscible in aU proportions. The mixtures are not simple soUd solutions but have a complex stmcture. Like the sulfides, the selenides exhibit semiconductor properties. 

Tellurium pseudohaUdes, such as the dicyanide [14453-24-8] Te(CN)2, the dithiocyanate [83543-04-8] Te(SCN)2, and thiourea complexes with Te(SCN)2, have been prepared. These are similar to the haUdes in properties. 

It is pertinent to record that the differences in the properties of compounds of selenium and tellurium in hydrochloric acid solution and the formation of several types of complex ion by these elements are the basis of extraction and ion-exchange methods of separating selenium and tellurium.1... 

Complexes of both selenium(IV) and tellurium(IV) with sulfur-containing ligands are known although the structural properties appear to have been determined only for the tellurium(IV) species. However, due to the smaller size of selenium(IV) and its poorer acceptor properties, as compared with tellurium(IV), its maximum coordination number appears to be six whilst it has been found to be eight for tellurium.78 Furthermore, the greater tendency of tellurium to form secondary bonds may cause the structures of similar selenium(IV) and tellurium(IV) compounds to be different. 9 It is also pertinent to note that the reduction of tellurium(IV) to... 

Thus far only eight different types of five-membered heterocycles with two heteroatoms, one of these being tellurium, are known. Of special interest are those containing S,Se, or Te as the second heteroatom in the ring. Such compounds afford electron-donor components of charge-transfer complexes or radical cation salts, exhibiting properties of the so-called organic metals. 

The ability to control product formation, the reproducibility of results, and the relatively mild conditions under which the reactions proceed, have made cluster syntheses by this method very attractive. Furthermore, the starting materials are themselves readily prepared and easily stored and handled. This is especially valuable in metal telluride chemistry, in which suitable reagents for cluster syntheses are often unstable and must be generated in situ, leading to complex mixtures of reaction products. The use of the silylated tellurium reagents Te(TMS)2 and RTe-TMS has allowed access to a wealth of metal tellurium clusters with unique structures and properties. " ... 

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