Tellurium Pentafluoride

Phenyl tellurium pentafluoride, easily prepared from diphenyl ditelluride and xenon difluoride (Xep2), reacts smoothly with olefins affording the corresponding 1,2-difluorides. ... 

Methoxy tellurium pentafluoride and sodium methoxide (molar ratio 1 8) in methanol in a sealed tube at 20° produced, after 18 hours, a mixture offac- and mer-trimethoxy tellurium trifluoride1. The composition of the reaction mixture was ascertained by 19F-NMR spectroscopy. 

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 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. 

Ethoxy Methoxy Tellurium Tetrafluorlde1 1.0 g (3.7 mmol) of ethoxy tellurium pentafluoride are dissolved in 10 m/ of carbon tetrachloride, 0.4 g (12.5 mmol) of methanol are added, and the mixture is cooled to — 20u. 0.4 g (5.1 mmol) of pyridine are added dropwise to the cold solution, the mixture is extracted with very dilute hydrochloric acid to remove pyridinium fluoride, and the organic layer is separated, and dried with anhydrous sodium sulfate. The mixture is filtered, carbon tetrachloride is distilled off under reduced pressure, and the product is distilled under vacuum yield 0.65 g (63%) b.p. 65°/20 torr. 

Reactions of methoxy tellurium pentafluoride with alcohols also produced unsymmetrical methoxy alkoxy tellurium tetrafluorides but in lower yields than those achieved in reactions with methanol. Methoxy tellurium pentafluoride is partly lost through methylation of pyridine1. 

Amino tellurium pentafluorides are thermally rather unstable, moisture-sensitive compounds. 

Diethylamino tellurium pentafluoride and N-pyrrolidtno tellurium pentafluoride were similarly prepared, but the yields were variable and did not exceed 20%2. 

Equimolar amounts of tellurium hexafluoride and bis[trimethylsilyl]amine reacted at 20° in a stainless steel vessel and gave, after 12 h, trimethylsilylamino tellurium pentafluoride in almost quantitative yield1-3. 

Trimethylsilylamino Tellurium Pentafluoride 16.1 g (0.1 mol) of bis[trimethylsilyl]amine are placed in a 250 ml stainless steel vessel which is then cooled to —196°. 31.4 g (0.13 mol) of tellurium hexafluoride are condensed into the vessel which is then sealed, warmed to 20°, and stirred at this temperature for 12 h. The resultant mixture is distilled in a glass apparatus and the fraction boiling at 58°/12 torr is collected yield 31 g (100%) m.p. 9° b.p. 58°/12 torr. 

Chloro(trifluoromethyl)methyleneamino tellurium pentafluoride was similarly prepared2 from tellurium chloride pentafluoride and trifluoromethyl cyanide. The product could be purified only by preparative gas chromatography on a 15% Halocarbon K-352 column. The vapor pressure of the pure compound was 50 torr at 25°. 

Dichloroamino tellurium pentafluoride and bromotrimethylsilane formed chloro(tr t-methylsilyl)amino tellurium pentafluoride, as a yellow, moisture-sensitive liquid that decomposes slowly at room temperature to trimethylfluorosilane1. 

Chloro(trimethylsilyl)amino Tellurium Pentafluoride3 5.14 g (16.7 mmol) of dichloroamino tellurium pentafluoride, prepared from trimethylsilylamino tellurium pentafluoride and chlorine fluoride3, are dissolved in 10 m/ of fluorotrichloromethane, 2.75 g (18 mmol) of bromotrimethylsilane are added dropwise under protection from moisture, and the resultant solution is slirred at 20° for 2 h. The components of the mixture are separated by several trap-to-trap distillations with traps at —30°, —78°, and — 136° yield 3.17 g (55%) b.p. -3070.007 torr. 

Trimethylsilylamino tellurium pentafluoride treated with carbonyl difluoride at 60° produced carbonylamino tellurium pentafluoride7 . 

Carbonylamino Tellurium Pentafluoride3 3.1 g (10 mmol) of trimethylsilylamino tellurium pentafluoride are placed in a 100 ml stainless steel cylinder which is then cooled. 1.98 g (30 mmol) of carbonyl difluoride are condensed into the cylinder which is then closed and heated at 60° for 15 h. The resultant mixture is distilled under a dynamic vacuum through —78° and —196° traps. The contents of the —196° trap are pumped... 

Isocyanato tellurium pentafluoride added methanol to form methoxycarbonylamino tellurium pentafluoride, a colorless, crystalline material1. 

Methoxycarbonylamino Tellurium Pentafluoride1 0.11 g (3.4 mmol) of methanol and 1.08g (4.1 mmol) of isocyanato tellurium pentafluoride are condensed into a 100 ml stainless steel cylinder. The mixture is stirred overnight at 20°, the cylinder is evacuated to constant weight, and the solid residue is sublimed at 30°/0.075 torr onto a cold finger at —30° yield 0.24 g (25%) m.p. 77". 

Diehloromethyleneamino tellurium pentafluoride was converted by excess hydrogen fluoride to trifluoromethylamino tellurium pentafluoride, by heating with cesium fluoride to cesium pentafluorotellurof trifluoromethyl)amide, and by heating with mercury (II) fluoride to mercury bis pemafluorotelluro trifluoromethylamide]2 3. 

Trifluoromethylamino Tellurium Pentafluoride3,4 Into an autoclave at — 196" containing 3.8 g (11.9 mmol) dichloromethylenamino tellurium pentafluoride are condensed 3.9 g (195 mmol) of anhydrous hydrogen fluoride. The reaction mixture is warmed to 20° and then kept at 40- 50° overnight. The volatile products are placed over a sodium fluoride scrubber for 1 2 h. Repeated trap-to-trap distillation deposited Irifluoro-methylamino tellurium pentafluoride in the — 78° trap yield 3.3 g (90%). 

Mercury Bis[pentafluorotelluro trifluoromethylamide]3 14.2 g (44.6 mmol) of dichloromethyleneamino tellurium pentafluoride are condensed into a 100 ml stainless steel autoclave containing 48.0 g (201 mmol) of mercury (II) fluoride. The mixture is stirred and heated at 60° for4days. The autoclave is chilled to — 25° and any volatile materials removed at this temperature under vacuum. The remaining solid is sublimed at 60" onto a cold-finger at — 25° yield 17.8 g (98%) m.p. 67-68°. 

The chlorine atoms in dichloromethyleneamino tellurium pentafluoride were replaced by methoxide, when the tellurium compound and sodium methoxide in diethyl ether were kept at 20° for four days2. The products were dimethoxymethyleneamino and chloro(methoxy) methyleneamino tellurium pentafluoride. 

Trifluoromethylamino tellurium pentafluoride heated with potassium fluoride or mercu-ry(II) fluoride yielded the respective pentafluorotelluro(trifluoromethyl)amides2 3. 

Pyrolysis of potassium pentafluorotelluro(trifluoromethyl)amide produced difluoromethy-leneamino tellurium pentafluoride. This compound did not isomerize to trifluoromethyl-imino tellurium tetrafluoride2,3. 

When trifluoromethylamino tellurium pentafluoride and excess potassium fluoride were slowly warmed from — 78° to 0° over 12 hours and held at room temperature for six hours, [(trifluoromethylimino)fluoromethylamind tellurium pentafluoride was isolated by trap-to-trap distillation in the — 40° trap as a colorless, fairly nonvolatile liquid2. 

With methyl iodide the amide-nitrogen atom becomes methylated1, and with acetyl bromide, acetylated2. With chlorotrimethylsilane, difluoromcthyleneamino tellurium pentafluoride is formed2. 

Dialkylamino tellurium pentafluorides with dialkylaminotrimethylsilane produce bis[di-alkylamino] tellurium tetrafluorides3. 

Alkoxy tellurium pentafluorides are powerful alkylating agents and must be handled very carefully. The low molecular mass compounds are colorless liquids with a powerful odor. They are hydrolyzed only slowly by water and alkaline solutions. 

Hexamethoxy tellurium dissolved in anhydrous hydrogen fluoride had formed, after 24 hours at 60° some methoxy tellurium pentafluoride and all the other possible methoxy... 

Primary monohydric and polyhydric2 alkanols reacted with tellurium hexafluoride to form alkoxy tellurium pentafluorides. Primary alkanols and equimolar amounts of tellurium hexafluoride in the presence of sodium fluoride or pyridine gave alkoxy tellurium pentafluorides in yields generally higher than 70%3. 

Cholesteryloxy tellurium pentafluoride (m.p. 153°) was similarly prepared using 1,2-dimethoxyethane as the solvent. The compound was purified by column chromatography with benzene as the mobile phase4. 

The reaction of 2-/V-acetylaminoethanol with tellurium hexafluoride in acetonitrile produced an oxazolinium pentafluoro(oxo)tellurate(VI) from the intermediary 2-N-acetylaminoethoxy tellurium pentafluoride that underwent intramolecular alkylation4. 

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