Tellurium compounds tetrafluoride

The tetrafluorides of selenium and tellurium are similar to SF4 both structurally (in the gaseous molecules) and in terms of reactivity, ffowever, the bonding in condensed phases is different and leads to several types of structures. Selenium tetrafluoride can be prepared by combining the elements, but it can also be obtained by the reaction of Se02 with SF4 at high temperature. The tellurium compound can be prepared by the reaction of SeF4 and Te02 at 80 °C. 

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)]. 

Fluorination of tetraalkoxy tellurium compounds in fluorotrichloromethane at — 78° with fluorine diluted with nitrogen produced dialkoxy tellurium tetrafluorides among other alkoxy tellurium fluorides. The reactions were carried out as described on page 123. The mixture of products was characterized by 19F-NMR spectroscopy3. 

Organic tellurium compounds with one Te—C bond containing divalent, tetravalent, or hexavalent tellurium have been prepared. The most widely investigated and best characterized compounds are the diorgano ditellurium derivatives and the organo tellurium trihalides. Pentafluoroethyl tellurium chloride tetrafluoride is the only known example of a hexavalent tellurium compound with one Te-C bond in the molecule. 

Tellurium tetrafluoride and tellurium tetrachloride reacted exothermically with N,N-bis[trimethylsilyl]acetamide and with A, A -bis[trimethylsilyl]arenesulfonamides in benzene to precipitate the corresponding diimino tellurium compounds. ... 

Diaryl tellurium compounds are converted to diaryl tellurium dihalides through reactions with sulfur tetrafluoride triaryl bismuth difluorides , copper(II) halides iron(III) chloride, and mercury(II) chloride ... 

Sihcon and boron bum ia fluorine forming siUcon tetrafluoride [7783-61-17, SiF, and boron trifluoride [7637-07-2] respectively. Selenium and tellurium form hexafluorides, whereas phosphoms forms tri- or pentafluorides. Fluorine reacts with the other halogens to form eight interhalogen compounds (see Fluorine compounds, inorganic-halogens). 

Stable noble-gas compounds have no industrial uses as of this writing but are frequently utilized in laboratories as fluorinating and oxidizing agents. Xenon difluoride and xenon tetrafluoride are relatively mild oxidative fluorinating agents and have been used for the preparation of phosphoms, sulfur, tellurium. 

Although free from the formally oxidising anions present in the two groups below, a few of these compounds show instability. These are m-Bis(trimcthvlsilylamino )tellurium tetrafluoride, 2615 Pentaamminechlororuthenium chloride, 4137... 

The same compounds were obtained when tellurium tetrafluoride and three molar equivalents of tellurium tetrakis[fluoroalkoxides] were refluxed in benzene3. 

The same compounds were obtained by refluxing equimolar amounts of tellurium tetrafluoride and tellurium tetrakis[fluoroalkoxides] in benzene1. 

Bis[2-chloroethoxy] tellurium tetrafluoride reacted with ethanol to give bis[2-chloroethoxy] ethoxy tellurium trifluoride. However, this compound could not be obtained from 2-chloroethoxy ethoxy tellurium difluoride and 2-chloroethanol. Diethoxy tellurium tetrafluoride and 2-chloroethanol were also found to be unreactive1. 

Diamino tellurium tetrafluorides are thermally very unstable solids. These compounds were observed to explode. 

Equimolar amounts (0.1 mol) of tellurium hexafluoride and bis[trimethylsilyl]amine formed explosive cis-bis[trimethylsilylamino] tellurium tetrafluoride when heated at 60° in a steel cylinder3. The compound is a colorless crystalline material that can be sublimed at 40°/0.001 torr. 

Diethylamino dimethylamino tellurium tetrafluoride was formed by reacting dimethylamino tellurium pentafluoride with diethylaminotrimethylsilane or diethylamino tellurium pentafluoride with dimethylaminotrimethylsilane. The unsymmetrical bis[dialkylamino] tellurium tetrafluoride was detected in solution by 19F-NMR spectroscopy. The compound, however, was too unstable to be isolated2. 

The hydroxy methoxy tellurium tetrafluorides are surprisingly stable compounds. No hydrolysis or isomerization occurred in 96% sulfuric acid up to a temperature of 150°. The Pwi.v-compound seems to be thermodynamically more stable than the ds-derivative1. 

When a five-fold molar excess of boron trichloride was condensed on cis- or trans-hydroxy methoxy tellurium tetrafluoride and the reaction mixture warmed to 20", hydrogen chloride was liberated. After the hydrogen chloride evolution had ceased, an additional amount of boron trichloride was added. Removal of all volatile materials left the extremely moisture-sensitive boron tris[methoxo(oxo) tetrafluorotellurates (VI)] as residue. The compounds, obtained in quantitative yields, were purified by vacuum distillation3. 

Dialkoxy tellurium tetrafluorides with the same or two different alkoxy groups have been prepared. These compounds may exist as cis- and tram-isomers. Both isomers are colorless liquids that can be distilled under reduced pressure. They are only slowly hydrolyzed by concentrated alkali2. 

The reactions of alkoxy tellurium pentafluorides with alcohols in the presence of pyridine were used to prepare dialkoxy tellurium tetrafluorides with two different alkoxy groups in the molecule1. These unsymmetrical compounds are suspected to be predominantly in the cis-form. 

The compound dismutates slowly at low temperature and quickly at 20° to tellurium tetrafluoride and bis[pentafluorophenyl] tellurium difluoride1. 

The hydrolysis of phenyl tellurium pentafluoride with an equimolar amount of water in acetonitrile for one hour at 20 produced a 1 3 mixture of cis- and trcms pheriyl tellurium tetrafluoride hydroxides. The compounds were characterized by 19F-NMR spectroscopy. ... 

Tellurium tetrafluoride is a colorless crystalline solid, mp 130° with no measurable vapor pressure at room temperature. It is readily characterized by its Raman spectrum.4 The crystal structure of the compound shows TeF4 to be a polymeric bridged species In HF solution it forms salts of the type K+[TeFs ]. s... 

In the series of the binary halides of selenium and tellurium, the crystal structure determinations of tellurium tetrafluoride (100) and of tellurium tetrachloride on twinned crystals (65, 66) were the key to understanding the various and partly contradictory spectroscopic and other macroscopic properties (e.g., 66,161,168,169,219,220, 412), as well as the synthetic potential of the compounds. In contrast to the monomeric molecular i//-tbp gas phase structures with C2v symmetry (417), the solid state structures of both are polynuclear. As the prototype of the chlorides and bromides of selenium and tellurium, crystalline tellurium(IV) chloride has a cubane-like tetrameric structure with approximate Td symmetry (Fig. 1). Within the distorted TeCla+a octa-hedra the bonds to the triply bridging chlorine ligands are much longer than to the terminal chlorines. The bonding system can be described either covalently as Te4Cli6 molecules, or, in an ionic approximation, as [(TeCl Cn4] with a certain degree of stereochemical activity of the lone pairs toward the center of the voluminous cubane center (65, 66). 

Cis- and ranj-hydroxy methoxy tellurium tetrafluoride reacted stereospecifically with chlorotrimethylsilane tetramethylstannane, and boron trichloride with elimination of hydrogen chloride or methane. The compounds obtained are trimethylsiloxy methoxy tellurium tetrafluoride trimethylstannoxy methoxy tellurium tetrafluoride, and boron tris[methoxo(oxo)tetrafluorotellurate (VI)]... 

The HjC-O-Te bonds are remarkably stable no cis-trans isomerization was observed when the hydroxy methoxy tellurium tetrafluorides were kept at temperatures below 130°. The bonds are not cleaved by 65% oleum or chlorosulfonic acid at room temperature, instead, the sulfate esters HjCO-TeF tO-SOjH) were formed. These sulfate esters were transformed to HO-TeFiCO-SOjH) upon heating to 100°. Cesium chloride dissolved in an excess of cis- or /run.s-hydroxy methoxy tellurium tetrafluoride liberated hydrogen chloride with the formation of very hygroscopic cesium methoxo(oxo)letrafluorotellurates(VI). Trunj-hydroxy methoxy tellurium tetrafluoride reacts instantaneously with water with loss of fluoride. The cu-compound is stable toward hydrolysis at room temperature. ... 

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