Tellurium Trifluoride

Tellurium tetrafluoride and dialkyltrimethylsilylamines, when refluxed in benzene until the evolution of fluorotrimethylsilane had ceased, produced bis[dialkylamino tellurium difluorides2. The reaction cannot be stopped at the dialkylamino tellurium trifluoride stage. 

When fluoroalkoxy tellurium trifluorides and WjV-bisftrimethylsilylJarenesulfonamides were refluxed in benzene, fluorotrimethylsilane and arenesulfonimino fluoroalkoxy tellurium fluorides were formed. 

Benzenesulfonimino 2,2,3,3-Tetrafluoropropoxy Tellurium Fluoride1 A solution of 9.0 g (30 mmol) of N,N-bis[trimethylsilyl]benzenesulfonamidc in 25 ml of benzene is added dropwise to a stirred solution of 9.5 g (30 mmol) of 2,2,3,3-tetrafluoropropoxy tellurium trifluoride in 15 ml of benzene. The mixture is heated under reflux until evolution of fluorotrimethylsilane ceases, the mixture is cooled, the precipitate collected, and recrystallized from benzene yield 9.1 g (70%) m.p. 201° (dec.)... 

When equimolar amounts of fluoroalkoxy tellurium trifluorides and fluoroalkoxytrimeth-ylsilanes were heated in benzene at 70° for two hours and the reaction mixtures worked up as described for the reactions between tellurium tetrafluoride and fluoroalkoxy trimeth-ylsilanes, bis[fluoroalkoxy] tellurium difluorides were obtained1. 

Fluoroalkoxy tellurium trifluorides are viscous, distillable, moisture-sensitive oils. The compounds can be stored for long periods at 20° in the absence of moisture. 

Fluoroalkoxy tellurium trifluorides condense with fluoroalkanols in benzene to yield bisffluoroalkoxy] tellurium difluorides2. 

Fluoroalkoxy tellurium trifluorides and (V,/V-bis[trimethylsilyl]benzenesulfonamides in refluxing benzene form fluoroalkoxy benzenesulfonimido tellurium fluorides2. 

Fluoroalkyl tellurium trifluorides are hydrolyzed by water to hydrogen fluoride, fluoroalkanol, and tellurium dioxide. An intermediate hydrolysis product could not be isolated2. 

Trialkoxy tellurium trifluorides may exist as/ac-isomers (three fluorine atoms define a face of the octahedron) and as mer-isomers (three fluorine atoms at three corners along the circumference). The compounds are colorless liquids or solids. Although many trialkoxy tellurium trifluorides have been observed by I9F-NMR spectroscopy to be present in reaction mixtures, only a few were isolated in pure form. 

Hexamethoxy tellurium dissolved readily in anhydrous hydrogen fluoride. After heating the mixture at 60° for 24 hours, the reaction appeared to have been complete. All possible methoxy tellurium fluorides, among ihem jac-trimethoxy tellurium trifluoride, were present in the mixture. The components of the mixture were not separated but identified by 10F-NMR spectroscopy2. 

Tellurium hexafluoride reacted with an equimolar amount or an excess of 1,1,1-tris[hydroxymethyl]ethane in the presence of sodium fluoride (or pyridine) to give the alkoxy tellurium trifluoride as the only product3. 

Tellurium hexafluoride when heated with at least 4.5 molar equivalents of a primary alcohol at 90° for nine days in the presence of a large excess of sodium fluoride, produced mixtures of alkoxy tellurium fluorides. Among these fluorides were fac- and nzer-trialkoxy tellurium trifluorides. The compounds were identified by 19F-NMR spectroscopy1. The reactions were carried out as described on page 123. 

Dialkoxy tellurium tetrafluorides may react in chloroform with an excess of alcohol in the presence of pyridine to form trialkoxy tellurium trifluorides. Whether or not these reactions produce trialkoxy tellurium trifluorides depends on the nature of the alkoxy groups in the dialkoxy tellurium tetrafluoride and only secondarily on the nature of the alkyl groups of the alcohol. 

Trialkoxy Tellurium Trifluorides/Diamino Tellurium Tetrafluorides... 

The reaction mixtures were treated with water and the chloroform layers separated. The solvent was removed from the dried organic phases and the residues distilled under reduced pressure. The constitution of the products was confirmed by 19F-NMR spectroscopy. The trialkoxy tellurium trifluorides were found to be mixtures of the fac- and mer-isomers1. 

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. 

Organo tellurium trifluorides, trichlorides, tribromides, and triiodides are known. Aryl tellurium trihalides are generally more stable than alkyl tellurium trihalides. The sensitivity toward atmospheric agents decreases from the trichlorides to the triiodides. Very few organo tellurium trifluorides have been prepared and little is known about their reactivity. The general reactivity of aryl tellurium trihalides decreases from the chlorides to the iodides. 2-Chloroalkyl tellurium trichlorides, products of the addition of tellurium... 

Fluorination with elemental fluorine diluted 1 20 with nitrogen was used to prepare pentafluorophenyl tellurium trifluoride from bis[pentafluorophenyl] ditellurium at — 60° with fluorotrichloromethane as the reaction medium. The yield in this reaction was 80% 4-Methoxyphenyl tellurium trifluoride was obtained by electrochemical oxidation of the diaryl ditellurium in 0.5 M hydrofluoric acid at platinum electrodes2. Bisfpentafluoroethyl] ditellurium and chlorine fluoride (1 6) reacted at — 78° to give pentafluoroethyl tellurium trifluoride, a white solid melting at 95°3. The same compound was obtained with xenon difluoride as the fluorinating agent and melted at 143°4. 

Bis[pentafluoroethyl] ditellurium reacted with a slurry of xenon difluoride/sulfuryl fluoride in the temperature range — 45 to 20°. Pentafluoroethyl tellurium trifluoride was obtained as a crystalline solid in quantitative yield5. 

Pentafluorophenyl tellurium trifluoride was similarly obtained from the ditellurium compound and xenon difluoride in acetonitrile1. 

Pentafluorophenyl tellurium trifluoride remains as a moisture-sensitive, colorless solid yield 80% m.p. 102-103" (dec.). 

Methoxyphenyl Tellurium Trilluoride1 A 100 ml two-necked flask fitted with a magnetic stirrer and a reflux condenser is charged with 1.3 g (6 mmol) of silver fluoride and 30 ml of dry toluene. The stirred suspension is heated to reflux, 0.68 g (2 mmol) of 4-methoxyphenyl tellurium trichloride are added in small portions, and refluxing is continued for 3 h. The mixture is allowed to cool to 20°, silver chloride is filtered off, and fight petroleum is added to the filtrate. The precipitated product is collected and dried m.p. 176 178 . 4-Ethoxy phenyl tellurium trifluoride (m.p. 204°) was similarly prepared. 

Phenyl tellurium trifluoride and xenon difluoride in dichloromethane react at — 10° to give phenyl tellurium pentafluoride1. 

From Alkyl Tellurium Trifluorides and Cesium Fluoride... 

When a mixture of cesium fluoride and pentafluoroethyl tellurium trifluoride was heated for one hour at 100°, cesium pentafluoroethyltetrafluorotellurate(IV) was obtained3. 

Phenyl tellurium pentafluoride was obtained by treatment of diphenyl ditellurium or phenyl tellurium trifluoride with xenon difluoride2. 

Equimolar amounts of tellurium tetrafluoride and fluoroalkoxytrimethylsilane reacted in benzene at 60° to give fluoroalkoxy tellurium trifluorides. ... 

Tetrafluoropropoxy Tellurium Trifluoride 6.1 g (30 mmol) of tellurium tetrafluoride are suspended in 50 m/ of anhydrous benzene, the suspension is stirred, and 6.1 g (30 mmol) of 2,2,3,3-tetrafluoro-l-trimethylsiloxypropane are added dropwise. The mixture is heated at 60° for 1 h, filtered, fluorotrimeth-... 

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