Oxatellurolium Compounds

2-Chlorocarbonylethen-l-yl aryl tellurium derivatives, when dissolved in dichloromethane, isomerized in the presence of aluminum chloride to 1,2-oxatellurolium halides.  

5-Naphthyl-3-phenyl-l,2-oxatellurolium Chloride 1.0 g (2.4 mmol) of 2-chlorocarbonyl-l-phenylethenyl 1-naphthyl tellurium is dissolved in 10 m/ of dry dichloromethane and the solution is cooled under nitrogen to — 78°. 0.35 g (2.6 mmol) of aluminum chloride arc added, the cooling bath is removed, and the mixture is allowed to warm to 20°. It is carefully poured into 200 ml of ice/water and extracted with three 50 ml portions of dichloromethane. The combined extracts are dried with anhydrous sodium sulfate, the solvent is evaporated, and the solid residue is recrystallizcd from methanol yield 0.82 g (82%) m.p. 135°. Examples of similarly prepared 1,2-oxatellurolium chlorides are  

5-phenyl-1,2-oxatellurolium chloride 3-methyl-5-phenyl-l, 2-oxatellurolium chloride 

5-diphenyl-1,2-oxatellurolium chloride 5- (2-methylphenyl) -3-phenyl-1,2-oxa-tellurolium chloride 

The chloride in 2-oxatellurophenium chlorides was exchanged for fluoride, bromide, iodide, or trifluoroacetate.  

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Oxatellurolium compounds are stable in air as solids and in solution. They are not decomposed by light. Thermolysis at temperatures up to 300° and irradiation with unfiltered light from a Hanovia 450-V lamp failed to deposit tellurium. An X-ray structural study of 5-f4-methoxyphenyl)-3-phenyl-1,2-oxatellurolium chloride showed the Cl — Te —O bonds to be linear and to have bond orders of approximately 0.5. ... 

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