Reductions to Tellurols and Tellurolates

Dialkyl and diaryl ditellurium compounds are easily reduced to tellurols and tellurolates. Alkali metals in liquid ammonia or in an inert organic solvent, sodium borohydride in methanol, ethanol, alcohol/benzene, THF, DMF, or in a basic aqueous medium, lithium aluminum hydride in dioxane or THF/hexamethylphosphoric triamide, and thiourea dioxide in THF/50% aqueous sodium hydroxide have been used as reducing agents (p. 164). The tellurolates are easily oxidized in air. For this reason they are almost always used in situ. 

Reactions with Halogens, Xenon Difluoride, Thiocyanogen, Bis[thiocarbamoyl] Disulfides, A, A-Dihalobenzenesulfonamides, Thiols, and 

Elemental chlorine, bromine, and iodine, sulfuryl chloride and thionyl chloride convert diorgano ditellurium compounds to organo tellurium trihalides (p. 314). The reactions are carried out in inert organic solvents with stoichiometrically required amounts of reagents. Dialkyl ditellurium compounds may lose alkyl halides if the halogenolysis is not performed under mild conditions at low temperatures. When equimolar amounts of halogens and diaryl ditellurium derivatives are combined in appropriate solvents, aryl tellurium halides are formed (p. 239). The formation of aryl tellurium halides is facilitated by stabilizing substituents in the ort/io-position to the tellurium atom or by the presence of thioureas or selenoureas in the reaction mixture. 

Diphenyl ditellurium and xenon difluoride produced phenyl tellurium pentafluoridef Bis[pentafluorophenyl] ditellurium and xenon difluoride or fluorine diluted with nitrogen at low temperatures yielded pentafluorophenyl tellurium trifluoride. Similar reactions were carried out with bis[pentafluoroethyl] ditellurium.  

Thiocyanogen and diaryl ditellurium derivatives react in dry methanol in the dark at — 10° to form unstable aryl tellurium thiocyanates that were isolated as adducts with neutral N-, 0-, or S-donor ligands.  

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