Tellurium xanthates

Structural Data for Binary Tellurium Xanthates, Te(S2COR)2... 

The molecular structure of Te(S2COEt)(S2CNEt2) (262) is shown in Fig. 163 and it becomes immediately evident that the coordination geometry is the same as that found for the binary tellurium xanthates described above. The xanthate ligand forms Te—SI and Te—S bond distances of 2.535(2) and 2.911(3) A, respectively, and these are longer than the corresponding distances formed by the dithiocarbamate ligand of 2.489(3) and 2.801(3) A, respectively. This key... 

There are single examples of sulfur and selenium xanthates with the remaining structures to be described in this section featuring tellurium as the central element. There are a significant number of binary xanthates and, in common with these, their organotellurium xanthates feature extensive supra-molecular association, usually, but not exclusively, via Te- S secondary bond interactions. A rare example of mixed-ligand 1,1-dithiolate structure is available where the odd dithiolate ligand is a dithiocarbamate. 

Figure 164. Two views of the molecular structure of the anion in fNEt4][Te(S2COMe)3] (a) showing the orthogonal relationship between the S5, S6 xanthate ligand and the remaining xanthate ligands and (b) highlighting the planar coordination about the tellurium atom.

The third diorganotellurium structure to be described has a chelating tellurium-bound organic group. In the molecular structure of [C6H4(CH2)2]Te(S2-COEt)2 (272), shown in Fig. 170, the two xanthate ligands form asymmetric... 

Tellurium (VI) fluoride, 1 121 Tellurium(IV) oxide, 3 143 Tellurium (II) xanthates, 4 91 Tetrabutylammonium dibromo-bromate(I), 5 177 Tetrabutylammonium dichloro-iodate(I), 5 174... 

Selenium and tellurium dioxides react with alkali xanthates and dithiocarbamates to give xanthates and dithiocarbamates of selenium(IV) and tellurium(IV).1,2 Russell1 states that the product formed by sodium diethyldithio-carbamate and selenium dioxide sometimes appears as an equimolar mixture of selenium (II) dithiocarbamate and the corresponding bis(thiocarbamyl) disulfide, (R2NCS)2S2. The commercial selenium dithiocarbamates, prepared by the above-mentioned method, usually consist of such mixtures. The disulfide can, in most cases, be extracted from selenium (II) dithiocarbamate by means of cold benzene or chloroform. 

Xanthates and dithioearbamates of bivalent selenium and tellurium may be conveniently prepared3-5 by allowing sodium selenopentathionate or sodium telluropenta-thionate to react with alkali xanthates or dithiocar-bamates. The reactions are rapid and quantitative, and the products separate from the aqueous reaction mixtures in a high state of purity. 

The selenium derivatives of xanthates and dithiocar-bamates are greenish yellow the tellurium compounds are red In the solid state, the dithioearbamates are quite stable, while the xanthates decompose after a few days, liberating selenium or tellurium. The compounds are insoluble in and unaffected by water. The decomposition of the selenium compounds into selenium and disulfides is strongly catalyzed by xanthates and dithiocarbamate ions. The uncorrected melting points are summarized in Table I. 

Diorgano tellurium bis [(9-alkyl xanthates] decompose thermally to give the diorgano tellurium and bis [O-alkylthiocarbonyl] disulfide1,2. 

Dimethyl Tellurium Bis[alkyl Xanthate]6 A solution of 20 mmol of the dimethyl tellurium dialkoxide in absolute benzene is mixed with 200 mmol absolute carbon disulfide. The mixture is stirred at 30 to 35° for 3 h. The excess carbon disulfide is removed under reduced pressure. Pentane is added to the benzene solution and the mixture is cooled to crystallize the product ... 

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