Tellurides, diphenyl

The oxidation potentials of diphenyl selenides ° and diphenyl tellurides have been measured by electrochemical methods, as well as by pulse radiolysis. Pulse electrolysis was used to determine E° values for diphenylsulfide (84), diphenylselenide (85), and diphenyltelluride (23). In each case, equilibrium... 

Diorganyl tellurides have low molecular mass and are colourless or yellowish liquids with an unpleasant and penetrating odour. Dimethyl teUuride is a metabolite of tellurium and tellurium compounds in a variety of living organisms, including humans. Higher dialkyl tellurides and most diaryl tellurides are solids with low melting points (diphenyl telluride is a liquid). 

With sodium sulphide hydrate (general procedure) The diorganyltellurium dihalide is mixed with a 15 times molar excess of Na2S 9H2O and the mixture heated at 95-100°C for 10 min or more, until aU the solid has melted. Sufficient HjO is added to dissolve the sulphide and then the mixture is filtered if the obtained telluride is a solid, or extracted with a solvent (ether or petroleum ether) if the telluride is a liquid. The products are purified by crystallization or distillation. Yields are high or quantitative (except for diphenyl telluride or di-p-tolyl telluride). 

Another group of methods involves the conversion of the tellurium into some compound, inorganic or organic, which can be purified and then made to regenerate the element. Hydrogen telluride,7 crystalline telluric acid,8 basic tellurium nitrate 9 and diphenyl telluride 10 have all been made use of. 

The dichloride reacts with magnesium phenyl bromide, CeHs.MgBr, in ether solution, with formation of diphenyl telluride, (C6H5)2Te. Tellurium dibromide and di-iodide give a similar result.8 In ether solution the dichloride absorbs bromine and iodine, but the products, presumably the chlorobromide and chloro-iodide, respectively, have not been isolated.9... 

By treating aryl magnesium bromides in ether solution with tellurium dibromide (in the case of diphenyl telluride the by-products consist of diphenyl ditelluride, diphenyl and tellurium). 

Diphenyl benzyl tellurium bromide,1 (CeH5)2(C6H5.CH2)TeBr, from diphenyl telluride dissolved in benzyl bromide, forms a crystalline mass, M.pt. 90° to 91° C., converted by silver hydroxide into the corresponding hydroxide, a yellow oil, very soluble in water, and yielding a sparingly soluble picrate on treatment with picric acid. 

Diphenyl tellurium dibromide, (C6H5)2TeBr2, occurs when diphenyl telluride reacts with bromine,3 or when the bromine is replaced by hydrobromic acid and the process conducted in the manner described for the corresponding dichloride.4 The dibromide may be crystallised from chloroform, melts at 203 5° C., and when heated to 280° C. the bromine still remains attached to the tellurium atom. It forms crystals belonging to the tetragonal system and a second modification which is triclinic and gives the following values 5... 

Diphenyl tellurium di-iodide,1 (C6H5)2TeI2, separates as a red precipitate wThen an ether solution of iodine is added to a similar solution of diphenyl telluride. It crystallises from chloroform as small, Bordeaux-red crystals, M.pt. 237° to 238° C. on rapid heating. It is slightly soluble in benzene, toluene, ligroin or alcohols. 

Diphenyl-telluretin bromide methyl ester,2 (C6Hs)2Te(Br). CH2.COOCH3, is obtained by the interaction of diphenyl telluride and methyl bromacetate. It is a white powder, M.pt. 99° to 100° C., very soluble in hot water and separating on cooling as prismatic crystals, M.pt. 105° to 106° C. Boiling alcohol splits it up into its components. The corresponding ethyl ester melts at 63° to 64° C. 

Diphenyl-telluretin bromide, (C6H5)2Te(Br).CH2.COOH, is the condensation product of diphenyl telluride and bromacetic acid, but has not been isolated in the solid state. The chloride, picrate and platinichloride have not been obtained in a pure state. 

Diphenyl-telluretin iodide ethyl ester,1 (C6H5)2Te(I)CH2. COOC2H5, is isolated from diphenyl telluride and ethyl iodo-acetate. It forms yellow crystals, readily soluble in chloroform and melting at 110° C. 

Diphenyl-a-propionyl-telluretin bromide, (C6H5)2Te(Br). CH(CH3)COOH, from a-bromopropionic acid and diphenyl telluride, is an amorphous powder, sintering at 50° C. and melting at 98° C. The analysis of this product does not give good results. 

Dihydrotellurophene-1,1-difluoride119 was formed in the low-temperature reaction of 2,5-dihydrotellurophene with xenon difluoride. Aryltellurium(Vl) fluoride was synthesized from diaryl ditelluride or aryltellurium(lV) fluoride120 while perfluorinated dimethyl or diphenyl tellurides are transformed only to difluorides121,122 (Scheme 51). 

While organic tellurium derivatives are often thought to be malodorous, this reputation is deserved only by the light alkyl derivatives. With the exception of diphenyl telluride, the aromatic derivatives are solids at room temperature. 

As a second example of chemical properties we have considered peak oxidation potentials of 4,4 -disubstituted diphenyl selenides and diphenyl tellurides. We consider these quantities to be chemical properties because no covalent bonds have been formed or broken. The best regression equations obtained were for the selenides ... 

Finally, we have correlated the Te chemical shifts of the 4,4 -disubstituted diphenyl tellurides, obtaining... 

The reactions of iron carbonyls with diorgano tellurides deserve mention, for example the reaction of Fe3(CO),2 with PhjTe gives Ph2TeFe(CO>4, whilst several ruthenium-carbonyl complexes have been prepared from reactions between diphenyl telluride and alcoholic carbon monoxide-saturated solutions of ruthenium trichloride hydrate. Various other ruthenium-carbonyl complexes of diorgano teUurides, including di- and tri-substituted species, have also been described. The utility of diphenyl telluride in transition metal carbonyl chemistry has also been well illustrated during studies of manganese and rhenium compounds. 

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