Phosphane Telluride

Tellurium inserts into the P-group IV element bond in trialkylsilyl(-germyl, -stannyl)-diorganophosphanes in a benzene medium. The reaction proceeds via phosphane tellurides that rearrange to compounds with a P —Te-group IV element bond1-3. 

Fhosphane tellurides are pale-yellow solids. Most of these compounds are very sensitive to oxygen and decompose with deposition of tellurium when heated. Some of the compounds are light-sensitive. Phosphane tellurides can be stored under an inert atmosphere at low temperatures. The X-ray structure1 of tri(f-butyl)phosphane telluride and the 31P- and 125Te-NMR spectra of trialkylphosphane tellurides1,2 were reported. 

Phosphane tellurides could not be isolated from the reaction mixtures containing alkyldiphenylphosphanes, triphenylphosphane1, or tetrakis(bis[diphenylphosphano] methyl)methane3 and tellurium. 

Tris[diethylamino]phosphane and bis[dimethylamino]organophosphanes form phosphane tellurides when heated with tellurium in a sealed tube at 160° under an inert atmosphere4,5. 

Tris[dimethylamino phosphane telluride was obtained in 76% yield by stirring the reagents in benzene/pentane (4 1, v/v) for 20 h at 20°. The compound was recrystallized by cooling a benzene/hexane solution (15 85, v/v) from 40° to 0°. The pale, yellow-green crystals are stable at 0°6. 

Diaza-2,4-diphosphetidines react with tellurium to form phosphane tellurides in benzene at 20°1,2 or at reflux temperature3,4. 

Alkylbis[ethoxy]phosphanes and tellurium formed phosphane tellurides on heating the reagents in neat form5 or in a medium of benzene6. 

Impure ethyl(diethoxy)phosphane telluride was obtained as an unstable yellow liquid by heating ethyl(diethoxy)phosphane and tellurium1 or reacting dichloroethylphosphane with ethanol and tellurium in benzene in the presence of triethylamine2. Dichloromethyl-phosphane did not react with tellurium3. 

The P = Te group is the most reactive part in phosphane tellurides. 

Tri-f-butylphosphane telluride and tris[dimethylamino]phosphane telluride combined with the corresponding phosphanes to give bis[triorganophosphane] tellurium derivatives. ... 

Tri-f-butylphosphane telluride reacted with the hexacarbonyls of chromium, molybdenum, and tungsten in tetrahydrofuran under illumination4 to yield stable phosphane telluride complexes (CO)5M-Te=PR3... 

A series of phosphane tellurides replaced tetrahydrofuran in cyclopen tadienyldicarbon-yl(tetrahydrofuran)iron(II) tetrafluoroborate5 to produce fairly air-stable, solid brown complexes in yields between 65 and 88%. 

Triethylphosphane telluride formed mercury telluride when refluxed in toluene in the presence of elemental mercury, diethyl mercury, or diphenyl mercury1. Phosphane tellurides and methyl iodide in benzene under an inert atmosphere produce at room temperature methyltellurophosphonium iodides2. 

The solid is stable toward sunlight and moist air. A single-crystal X-ray structural analysis showed the P —Te —P group to be linear with P — Te bond lengths of 238.8 and 341.2 pm4. Mixtures of tri-/-butylphosphane telluride/tri-/-butylphosphane or tris[dimethylamino] phosphane telluride/tris[dimethylamino]phosphane in toluene were observed by NMR spectroscopic methods to form compounds with a P-Te-P group5. 

At a molar ratio of phosphane telluride to diphenyl mercury of less than two, very little diphenyl ditellurium is formed. 

Trialkylphosphane tellurides, dimorpholinophenylphosphane telluride, tris[5cc-ami-no]phosphane tellurides, and trialkoxyphosphane tellurides in acetone solution transfer tellurium to cyanide forming tellurocyanate. The extent of this transfer is determined by the groups bonded to the phosphorus atom. The equilibrium can also be reached by reacting phosphanes with tellurocyanate. ... 

Tellurocyanates converted tertiary phosphanes to phosphane tellurides The equilibrium constant for this reaction varies with the nature of the groups bonded to phosphorus. ... 

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