From Potassium Tellurocyanate and Arenediazonium Tetrafluoroborates

Diaryl tellurium compounds can be obtained in moderate yields from potassium tellurocyanate and arenediazonium tetrafluoroborates in DMSO at room temperature. The potassium tellurocyanate is obtained from tellurium and potassium cyanide in DMSO. Aryl tellurium cyanides are probably formed as intermediates that disproportionate to the diaryl tellurium products and tellurium dicyanide.  

6-tribromophenyl] Tellurium A 100-m/, two-necked flask equipped with a reflux condenser, a magnetic stirrer, and a nitrogen inlet is flushed with nitrogen. Into the flask are placed 1.6 g (12.5 mmol) of freshly crushed and finely ground tellurium, 0.82 g (12.5 mmol) of potassium cyanide, and 20 ml of dry DMSO. The mixture is stirred and heated at 100° for 1 h. After all the tellurium has dissolved, the flask is cooled in an ice bath until most of the solvent has solidified. Then 5.4 g (12.5 mmol) of solid 2,4,6-tribromobenzenediazonium tetrafluoroborate are added rapidly. When the initial violent evolution of nitrogen has ceased, the ice bath is removed, the mixture is allowed to warm to 20°, and is stirred for 3 h. The mixture is poured into 250 ml of dichloromethane, filtered, and the filtrate washed several times with water. The organic phase is dried with anhydrous calcium chloride and the solvent is evaporated. The residue is dissolved in dioxanc. Copper powder is added, and the mixture is heated under reflux to convert any diaryl ditellurium to diaryl tellurium. The mixture is filtered, the filtrate is evaporated, and the residue is purified by chromatography on silica gel with dichloromethane as eluent yield 2.1 g (44%) m.p. 191°. 

Examples of diaryl tellurium compounds prepared in this manner are  

From Alkali Metal or Halomagnesiiun Organic Tellurolates 

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