Tellurium metal fluorides

Fluor-jod, n. iodine fluoride, -kalium, n. potassium fluoride, -kalzium, n. calcium fluoride, -kiesel, m. silicon fluoride, -kie-selsaure,/. fluosilicic acid, -kohlenstoff, m. carbon fluoride, -lithium, n. lithium fluoride. -metall, n. metallic fluoride, -natrium, n. sodium fluoride, -phosphat, n. fluophosphate. -phosphor, m. phosphorus fluoride, -salz, n. fluoride, -schwefel, m. sulfur fluoride, -selen, n. selenium fluoride, -silber, n. silver fluoride, -silikat, n. fluo-silicate. -silizium, n. silicon fluoride, -sili-ziumverbindung, /. fluosilicate. -tantal-sMure, /. fluotantalic acid, -tellur, n. tellurium fluoride, -titan, n. titanium fluoride, -toluol, n. fluorotoluene, fluotoluene. 

Te(OH) forms adducts with alkali-metal fluorides such as Te(OH) -NaF or Te(OH)8-2KF (102). Single-crystal X-ray diffraction shows that, contrary to the earlier assumption, there is no direct bonding of fluorine to tellurium. The fluoride ions are incorporated into the structure by short O—H F hydrogen bonds (6, 7). 

Tellurium hexafluoride itself has been found to form complexes with potassium, rubidium and cesium fluorides. The cesium compound has a stochiometry approaching Cs2TeF8 and, in these types of complexes, the stability of the lattice appears to be inversely related to the polarizing power of the cation and the compounds are only stable in the solid state.41 Several heptafluorotellurates(VI) have been prepared from the reaction of tellurium with chlorine trifluoride in anhydrous hydrofluoric acid followed by addition of the metal fluoride.42... 

Diaryl tellurium dichlorides, obtainable from aromatic compounds and tellurium tetrachloride, react with excess bromine or iodine in refluxing DMF or acetonitrile in the presence of a metal fluoride to give aryl halides in low yields. The reactions with chlorinating agents are very sluggish. The reaction of bromine and bis[4-methoxyphenyl] tellurium dichloride formed 2,4-dibromomethoxybenzene in 76% yield. Reactions of these tellurium dichlorides with copper(I) cyanide in DMF produced aryl cyanides in yields of less than 8%3. 

Tellurium hexafluoride is hydrolysed by water to telluric acid, HfiTeOfi (16.62), and undergoes a number of exchange reactions such as reaction 16.77. It is also a fluoride acceptor, reacting with alkali metal fluorides and [Me4N]F under anhydrous conditions (equation 16.78). 

Magnesium Air, beryllium fluoride, ethylene oxide, halogens, halocarbons, HI, metal cyanides, metal oxides, metal oxosalts, methanol, oxidants, peroxides, sulfur, tellurium... 

The magnetic criterion is particularly valuable because it provides a basis for differentiating sharply between essentially ionic and essentially electron-pair bonds Experimental data have as yet been obtained for only a few of the interesting compounds, but these indicate that oxides and fluorides of most metals are ionic. Electron-pair bonds are formed by most of the transition elements with sulfur, selenium, tellurium, phosphorus, arsenic and antimony, as in the sulfide minerals (pyrite, molybdenite, skutterudite, etc.). The halogens other than fluorine form electron-pair bonds with metals of the palladium and platinum groups and sometimes, but not always, with iron-group metals. 

Chlorine Non-metals Chlorine fluoride Tellurium Chlorine trifluoride Metals Fluorine Non-metals... 

Tellurium tetrafluoride combines with the fluorides of the alkali metals (including ammonium) and barium fluoride, producing colourless crystalline salts of the general formula XF.TeF4, in which X represents the equivalent weight of the metal.2... 

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... 

Uranium can be analysed as the hexafluoride, but the procedure requires modification of the chromatographic apparatus, nickel coating of metallic parts and nickel filaments in the katharometer [606], Tin in zirconium—tin alloys can be analysed as the chloride, prepared by treatment with chlorine [607]. Selenium and tellurium are converted into fluorides by treatment of their oxides with xenon difluoride [608]. 

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