Tellurium, liquid

Sulphur and tellurium form a chloride of formula XClj. Sulphur dichloride SClj is a red liquid at room temperature whilst the corresponding tellurium compound is a black solid. 

Gases and vapors of volatile liquids can be introduced directly into a plasma flame for elemental analysis or for isotope ratio measurements. Some elements can be examined by first converting them chemically into volatile forms, as with the formation of hydrides of arsenic and tellurium. It is important that not too much analyte pass into the flame, as the extra material introduced into the plasma can cause it to become unstable or even to go out altogether, thereby compromising accuracy or continuity of measurement. 

Since tire alkali and alkaline metals have such a high affinity for oxygen, sulphur aird selenium they are potentially useful for the removal of these iron-metallic elements from liquid metals with a lower affinity for these elements. Since the hairdling of these Group I and II elements is hazardous on the industrial scale, their production by molten salt electrolysis during metal rehning is an attractive alternative. Ward and Hoar (1961) obtained almost complete removal of sulphur, selenium and tellurium from liquid copper by the electrolysis of molten BaCla between tire metal which functioned as the cathode, and a graphite anode. 

Tellurium nitride was first obtained by the reaction of TeBt4 with liquid ammonia more than 100 years ago. The empirical formula TeN was assigned to this yellow, highly insoluble and explosive substance. However, subsequent analytical data indicated the composition is Tc3N4 which, in contrast to 5.6a and 5.6b, would involve tetravalent tellurium. This conclusion is supported by the recent preparation and structural determination of Te6N8(TeCl4)4 from tellurium tetrachloride and tris(trimethylsilyl)amine (Eq. 5.5). The TceNs molecule (5.12), which is a dimer of Tc3N4, forms a rhombic dodecahedron in which the... 

The sulfiu can be piped long distances in liquid form or transported molten in ships, barges or rail cars. Alternatively it can be prilled or bandied as nuggets or chunks. Despite the vast bulk of liquid sulfur mined by the Frasch process it is obtained in very pure form. There is virtually no selenium, tellurium or arsenic impurity, and the product is usually 99.5-99.9% pure. ... 

The two mixed tellurium(IV) halides listed in Table 16.5 were prepared by the action of liquid Br2 on TeCl2 to give the yellow solid TeBr2Cl2, and by the action of I2 on TeBr2 in ether solution to give the red crystalline TeBr2l2 their structures are as yet unknown. 

Tellurium and cadmium Electrodeposition of Te has been reported [33] in basic chloroaluminates the element is formed from the [TeCl ] complex in one four-electron reduction step, furthermore, metallic Te can be reduced to Te species. Electrodeposition of the element on glassy carbon involves three-dimensional nucleation. A systematic study of the electrodeposition in different ionic liquids would be of interest because - as with InSb - a defined codeposition with cadmium could produce the direct semiconductor CdTe. Although this semiconductor can be deposited from aqueous solutions in a layer-by-layer process [34], variation of the temperature over a wide range would be interesting since the grain sizes and the kinetics of the reaction would be influenced. 

Selenium and Tellerium Tantalum is attacked by selenium and tellurium vapours at temperatures higher than 80°C. Only slight attack is observed on the metal by liquid selenides and tellurides of ytirum, the rare earths, and uranium at temperatures of 1300 to 2100°C, and tantalum is considered to be a satisfactory material in which to handle these intermetallic compounds. 

Liquid tellurium boils at 990 °C to a golden yellow vapor, with density that corresponds to the molecular formula T 2- Likewise, in polonium vapor only P02 species are present. Clearly, the decreasing complexity of the solid state of the three elements Se, Te, and Po, as compared to sulfur, is reflected in the vapor state. 

The potential-pH diagram for the system tellurium-water at 25 °C is given in Fig. 2.4. It was constructed by using the following homogeneous and heterogeneous (solid/liquid, gas/liquid) equilibria, involving redox and non-redox processes, in which all of the above-referred dissolved substances of tellurium, as well as the solid ones, participate ... 

Mellor, 1941, Vol. 2, 292 1956, Vol. 2, Suppl. 1, 380 1943, Vol. 11, 26 Liquid chlorine at —34°C explodes with white phosphorus, and a solution in heptane at 0°C ignites red phosphorus. Boron, active carbon, silicon and phosphorus all ignite in contact with gaseous chlorine at ambient temperature. Arsenic incandesces on contact with liquid chlorine at —34°C, and the powder ignites when sprinkled into the gas at ambient temperature. Tellurium must be warmed slightly before incandescence occurs. 

Interaction with liquid ammonia at — 15°C forms tellurium nitride ( ), which explodes at 200°C. 

Sulfur vapor consists of a mixture of species that includes S8, S6, S4, and S2 (which like 02 is paramagnetic). Because the S8 molecule is nonpolar, it is soluble in liquids such as CS2 and C6H6. Selenium also consists of cyclic molecules that contain eight atoms, and tellurium is essentially metallic in character. In their vapors, several species are found that contain 2, 6, or 8 atoms. Both are useful as semiconductors, and selenium has been used in rectifiers. Because the electrical conductivity of selenium increases as the intensity of illumination increases, it has been used to operate electrical switches that open or close as a light beam is broken. Selenium was also used in light meters, but other types of meters are now available that are more sensitive. Table 15.1 gives a summary of the properties of the group VIA elements. 

Tellurium nitride is obtained by the reaction of TeBr4 with liquid ammonia. Analytical data indicated the composition is Te3N4 rather than Te4N4. This... 

Several explosive species in which three or more azido groups are bonded to tellurium have been well characterized.59 The salt [Te(N3)3][SbF6] is formed from the reaction of Te4[SbF6]2 with potassium azide in liquid sulfur dioxide. The neutral binary tellurium azide Te(N3)4 is prepared by the reaction of TeF4 (in CFC13)60 or TeF6 (in CH3CN)61 with trimethylsilyl azide. 

On the other hand, optically active telluroxides have not been isolated until recently, although it has been surmised that they are key intermediates in asymmetric synthesis.3,4 In 1997, optically active telluroxides 3, stabilized by bulky substituents toward racemization, were isolated for the first time by liquid chromatography on optically active columns.13,14 The stereochemistry was determined by comparing their chiroptical properties with those of chiral selenoxides with known absolute configurations. The stability of the chiral telluroxides toward racemization was found to be lower than that of the corresponding selenoxides, and the racemization mechanism that involved formation of the achiral hydrate by reaction of water was also clarified. Telluroxides 4 and 5, which were thermodynamically stabilized by nitrogen-tellurium interactions, were also optically resolved and their absolute configurations and stability were studied (Scheme 2).12,14... 

The dialkylaminotellurium(VI) pentafluorides are pale yellow liquids that decompose rapidly above 35°C. Bis(dimethylamino)tellurium(VI) tetrafluoride is a pale yellow solid, mp 57°C. The compounds have been characterized by IR, Raman, H-NMR, 19F-NMR, and mass spectroscopy. Reaction of (RaSi)2NH with TeF6 produces RaSiNHTeF5 (mp 9°C), which can be cleaved with HF to yield aminotellurium(VI) penta-fluoride (155) [Eq. (14)]. 

Certain volatile elements must be analyzed by special analytical procedures as irreproducible losses may occur during sample preparation and atomization. Arsenic, antimony, selenium, and tellurium are determined via the generation of their covalent hydrides by reaction with sodium borohydride. The resulting volatile hydrides are trapped in a liquid nitrogen trap and then passed into an electrically heated silica tube. This tube thermally decomposes these compounds into atoms that can be quantified by AAS. Mercury is determined via the cold-vapor... 

Diorganyl tellurides have low molecular mass and are colourless or yellowish liquids with an unpleasant and penetrating odour. Dimethyl teUuride is a metabolite of tellurium and tellurium compounds in a variety of living organisms, including humans. Higher dialkyl tellurides and most diaryl tellurides are solids with low melting points (diphenyl telluride is a liquid). 

Dichlorothiophenoxytellurine. o-Thiophenoxyphenyltellurium trichloride (2.1 g, 0.005 mol) was heated at 240-250°C in a glass tube with stirring for 30 min. Evolution of HCl was noted. On cooling, the dark liquid solidified to a dark yellow mass (1.9 g). This was dissolved in acetone, the solution filtered from a small residue of tellurium and crystallized, yielding needles (0.8 g, 42%), m.p. 265-270°C (at 230°C, a change in the crystalline form was noted). 

Sulphur, Selenium, and Tellurium Compounds.—The crystal structure of the metal-rich zirconium sulphide Zr Sj has been determined and each sulphur atom shown to be at the centre of a square antiprism of zirconium atoms. The reaction of ZrS2 with potassium in liquid ammonia has been shown to give four K ZrS2 phases (.x = 1, 0.86, 0.71, or 0.71—0.22) which differ in the nature of the co-ordination sites occupied by the potassium atoms between the ZrS2 layers. ZrCl reacts with NaS2P(OEt)2 in toluene to form [Zr S2P-(OEt)2 4], which appears to involve a trigonal-dodecahedral arrangement of sulphur atoms about the metal. ... 

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