Structural chemistry chalcogenides

The structural chemistry of the actinides is often similar to that of lighter transition metals, such as Zr and Hf, and to that of the lanthanides however, the diffuse nature of the 5/ orbitals leads to some differences and specifically to interesting magnetic and electrical properties. The actinide sulfides are generally isostructural with the selenides, but not with the analogous tellurides. The binary chalcogenides of uranium and thorium have been discussed in detail [66], but the structural... 

The platinum metal chalcogenides in general are easier to prepare than the corresponding oxides. Whereas special conditions of temperature and pressure are required to prepare many of the oxides, the platinum metals react most readily with S, Se, and Te. A number of additional differences concerning the chemistry of the chalcogenides and the oxides are summarized as follows The metal—sulfur (selenium, tellurium) bond has considerably more covalent character than the metal-oxygen bond and, therefore, there are important differences in the structure types of the compounds formed. Whereas there may be considerable similarity between oxides and fluorides, the structural chemistry of the sulfides tends to be more closely related to that of the chlorides. The latter compounds... 

The wealth of structural chemistry that has appeared over the past several years with metal-chalcogen nanoclusters has permitted the investigation and evaluation of the evolution of the properties of metal-chalcogenides on going from molecular to bulk solid systems. As is clear from the material reviewed in the preceding sections, these nanometer-sized solids continue to hold promise as novel electronic materials or low-temperature precursors to solids, although advanced practical ap-... 

The growing interest in gold-chalcogenide polynuclear chemistry can be attributed partly to the demonstration that these systems exhibit rich photoluminescence behavior, and partly to the interesting structural frameworks that are generated as a result of weak Au(I)-Au(I) interactions [85]. 

Kanishka Biswas obtained his Ph.D. degree from Solid State Structural Chemistry Unit, Indian Institute of Science, India (2(X)9), and did his postdoctoral research from Department of Chanistry, Northwestern University, USA (2009-2012). He is now a Assistant Professor (Faculty Fellow) in the New Chemistry Unit of Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore, India. He is an Associate of Indian Academy of Sciences, Bangalore. He is pursuing research in solid-state chanistry of metal chalcogenides and thermoelectric waste heat to electrical energy conversion . 

Betyllium, because of its small size, almost invariably has a coordination number of 4. This is important in analytical chemistry since it ensures that edta, which coordinates strongly to Mg, Ca (and Al), does not chelate Be appreciably. BeO has the wurtzite (ZnS, p. 1209) structure whilst the other Be chalcogenides adopt the zinc blende modification. BeF2 has the cristobalite (SiOi, p. 342) structure and has only a vety low electrical conductivity when fused. Be2C and Be2B have extended lattices of the antifluorite type with 4-coordinate Be and 8-coordinate C or B. Be2Si04 has the phenacite structure (p. 347) in which both Be and Si... 

Metal chalcogenides, apart from their technological significance in industrial applications, have played an important role in the development of new synthetic concepts and methods in the area of solid-state chemistry. A great example is alkali metal intercalation into TiS2 (Chap. 6) first reported three decades ago, which highlighted the then-novel synthetic approach called soft chemistry chimie douce). This low-temperature process allows for new compounds to be obtained while retaining the structural framework of the precursor. Related to this concept is the... 

R. Chevrel, Chemistry and structure of ternary molybdenum chalcogenides. Top. Curr. Phys. 32 (1982) 5. 

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