Tellurium dithiocarbamates

Tellurium bis[bis(2-hydroxyethyl)dithiocarbamate] and a thirty-fold molar excess of potassium bromide, iodide, or thiocyanate reacted in acetone acidified with acetic acid with replacement of one dithiocarbamate group per two molecules of tellurium dithiocarbamate by halide or thiocyanate. The deep-red crystals are stable as solids but decompose with deposition of tellurium when dissolved in methanol. The single-crystal X-ray structural analysis of the thiocyanato derivative revealed the presence of two chemically different tellurium atoms in the molecule that are in short contact1. 

In the thermochromic aryl tellurium tris[dithiocarbamates]3, all six sulfur atoms are bonded to the tellurium atom, providing a distorted pentagonal bipyramidal environment for tellurium4-5. In solution, the aryl tellurium tris[dithiocarbamates] reversibly dissociate to aryl tellurium dithiocarbamates and bis[thiocarbamoyl] disulfides3. 

Diorgano tellurium dithiocarbamate halides are isolated in quantitative yield from reaction mixtures containing equimolar amounts of a diorgano tellurium dihalide and an ammonium or sodium dithiocarbamate1,2. 

Examination of the diethyl ether extract by liquid chromatography (LC) using a Cjg reverse phase gradient elution separation with atmospheric pressure chemical ionisation (APCI) in the positive mode gave the total ion current trace shown in Figure 8.3. The last three peaks showed ions of masses 538, 566 and 594 and are believed to relate to the presence of tellurium dithiocarbamates in the extract (ions +2H from ionised protonic solvent). These species were not detected by GC-MS. 

Dithiobenzoic acid metal complexes, 2, 646 colours, 2, 646 Dithiobiuret metal complexes, 2, 640 Dithiocarbamates chelating resins mineral processing, 6,826 Dithiocarbamic acid metal complexes, 2,585 amine exchange, 1,428 photographic emulsions, 6,98 nickel poisoning, 6,768 tellurium(Il) complexes photothermography, 6,121 Dithiocarbazic acid metal complexes, 2,803 Dithiocarbimic acid metal complexes, 2,588 Dithiocarbimic acid, cyano-metal complexes, 2,808 Dithiocarboxylic acids metal complexes, 2,646 Dithiodiacetic acid metal complexes, 2, 806 Dithiodiketones... 

The structural chemistry of some metal dithiocarbamates, i.e. systematics, coordination modes, crystal packing, and supramolecular self-assembly patterns of nickel, zinc, cadmium, mercury,363 organotin,364 and tellurium,365 366 complexes has been thoroughly analyzed and discussed in detail. Supramolecular self-assembly frequently occurs in non-transition heavier soft metal dithiocarbamates. Thus, lead(II),367 bismuth(III)368 zinc,369 cadmium,370 and (organo)mercury371 dithiocarbamates are associated through M- S secondary bonds, to form either dimeric supermolecules or chain-like supramolecular arrays. The arsenic(III)372 and antimony(III)373 dithiocarbamates are... 

Simultaneous speciation of inorganic selenium and tellurium in water samples by ICP-MS was performed after selective solid phase extraction (SPE), as discussed by Yu et al 9 Under acidic conditions Se (IV) and (TV) complexes with ammonium pyrrolidine dithiocarbamate were formed. The detection limits for Se and species in water samples were found to be 7ngl 1 and 3 ng 1 1, respectively. 

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. 

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... 

Disulfur dinitride, 6 126 Disulfur pentoxydiehloride, 3 124 analysis of, 3 126 Dithiocarbamates, of selenium(II) and tellurium(II), 4 91 Dithionic acid, salts of, 2 167 Dithionite ion, formation of, from sulfur dioxide by sodium hydride, 5 13... 

Cyanate condensation products of carbohydrazide, synthesis 11 Thiosemicarbazide, synthesis 12 Dithiocarbamates of selenium(II) and tellurium (II), synthesis 32 Aluminum phosphide, synthesis 7 Phosphorus(III) fluoride, synthesis 49... 

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. 

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. 

Tellurium bis[dithiocarbamates] are red, crystalline solids that are decomposed by base to tellurium and tellurite1. The tellurium atom and the four sulfur atoms from the two dithiocarbamate groups form a plane with the sulfur atoms located at the corners of a trapezoid2-5. 

Mixing aqueous solutions of alkali tellurapentathionate and sodium dithiocarbamates precipitates tellurium bis[dithiocarbamates]6-9. 

Tellurium Bis[bis(2-hydroxyethyl)dithiocarbamate] 20 ml (50 mmol) of a 20% aqueous methanol solution of bis[2-hydroxyethyl]dithiocarbamic acid, prepared from carbon disulfide and bis[hydroxyethyl]amine, are slowly added to 5.0 g (10 mmol) of tetrakis[thiourea]tellurium dichloride are suspended in 50 ml of methanol containing 1 g of thiourea. The product separates as orange needles that are collected and recrystallizcd from methanol yield 4.4 g (90%) dec. 150°. 

Tellurium bis[0-ethyl dithiocarbonate] dissolved in chloroform is converted to insoluble tellurium bis[dithiocarbamate] upon addition of solutions of sodium dithiocarbamates in methanol or ethanol3,4. 

---