Tellurium tellurocyanates

However, selenium and tellurium do not react with hydrogen, so the hydrogen compounds are prepared by reacting the elements with a metal, then treating it with an acid. Selenium and tellurium undergo addition reactions with cyanides to yield selenocyanates and tellurocyanates ... 

The group VIB cyanides, thiocyanates and selenocyanates and their complexes with species such as thiourea have been described.1,45 For example, the tellurium dithiocyanate complex has been prepared45 by treatment of tellurium dichloride or tellurium dibromide with ammonium thiocyanate. It seems that little information exists on the preparation of tellurocyanates and there is a sparsity of data on polonium derivatives. Indeed, the only known cyanide of polonium is probably a salt of the quadrivalent element.1... 

Another approach to aryl tellurides involving nucleophilic tellurium species consists in the use of aryldiazonium salts as substrates. Arenediazonium tetrafluoroborates 64 react with sodium telluride,128 potassium tellurocyanate 65, sodium 0,0-diethylphosphorotellurolate 66, or aryl tellurolate 2 to give the corresponding diaryl tellurides 3 in moderate yields (Scheme 33).129,130... 

Although alkali metal cyanides react with tellurium in liquid ammonia4 or in dimethyl sulfoxide5 8 under an inert atmosphere, alkali metal tellurocyanates cannot be isolated from such solutions. Evaporation of the solvent leaves a residue of tellurium and the... 

Tellurocyanate ion reacts with benzyl halides1-3, aryl iodides10, arenediazonium tetraflu-oroborates4, and with azulene11 to form aryl tellurium cyanides. 

Potassium tellurocyanate, prepared from potassium cyanide and tellurium in DMSO, reacts with benzyl halides to produce benzyl tellurium cyanides in good yields. Because of the sensitivity of potassium tellurocyanate to oxygen and of some of the benzyl tellurium cyanides to light, the reactions must be carried out in an inert atmosphere (nitrogen or argon) under red light. 

Arenediazonium tetrafluoroborates react with potassium tellurocyanate in DMSO. The expected aryl tellurium cyanides are seldom stable enough to be isolable and are converted to diaryl ditellurium compounds. Only 2-nitrophenyl tellurium cyanide and 2,6-dimethyl-phenyl tellurium cyanide were obtained through chromatographic separation from the diaryl ditellurium compounds6. 

Azulenyl tellurium cyanide was synthesized from potassium tellurocyanate and azulene7. 

Diaryl tellurium compounds can be obtained in moderate yields from potassium tellurocyanate and arenediazonium tetrafluoroborates in DMSO at room temperature. The potassium tellurocyanate is obtained from tellurium and potassium cyanide in DMSO. Aryl tellurium cyanides are probably formed as intermediates that disproportionate to the diaryl tellurium products and tellurium dicyanide2. 

The nature of the noncoordinated end of the chalcogenocyanate group may also be used, with caution, to distinguish between N- and Se-bonded selenocyanates. The compound 7r-cpFe(CO)(PPh3)SeCN is stable but its N-bonded isomer readily deselenates at 27°C (410). Similarly, it is difficult to study Rh(I)—NCSe complexes because of rapid deselenation, and the loss of tellurium is a similar feature of tellurocyanate chemistry (36). 

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. ... 

Tetraphenylarsonium tellurocyanate and triphenylphosphane in acetonitrile formed bis[triphenylphosphane] tellurium. ... 

Bis[triphenyIphosphane] Tellurium 1.0 g (1.86 mmol) of tetraphenylarsonium tellurocyanate is dissolved in 20 ml of purified acetonitrile and 2.0 g (7.64 nunol) of triphenylphosphane are added under nitrogen. Then a solution of 0.34 g (3.2 mmol) of lithium perchlorate in 10 m/ of acetonitrile is added dropwise, the mixture is stirred at 20° for several min, 2.0 g of triphenylphosphane dissolved in 15 m/ of acetonitrile are added, and the mixture is stirred at 35° until the white precipitate has dissolved. The mixture is then filtered to collect the remaining yellow solid. This solid is dissolved in 20 ml of acetone containing 3.0 g of triphenylphosphine, the mixture is filtered, and the filtrate is kept at 0° for several hours until the first crystals of triphenylphosphine appear. The mixture is then filtered rapidly, the solid is washed with ice-cold acetone containing triphenylphosphine, and the solid is dried yield 0.36 g (30%) m.p. 83-85° (dec.). 

The tellurocyanate ion is stabilized by bulky onium cations. The reactions of tellurium with tetraethylammonium cyanide in dimethylformamide or acetonitrile , with tetramethyl-ammonium cyanide in acetonitrile , with tetraphenylarsonium cyanide in acetonitrile , or with bis[triphenylphosphane]iminium cyanide in acetone produced onium tellurocyanates that were isolated by evaporation of the solvent. The dry salts are reported to be unaffected by oxygen . Moist air and wet solvents decompose the tellurocyanates with depostion of tellurium . 

Tetramethylammonium Tellurocyanate To 250 ml of acetonitrile are added 26.4 g (0.24 mol) of tetramethyl-ammonium chloride and 31.0 g (0.48 mol) of potassium cyanide and the mixture is stirred. Precipitated potassium chloride is filtered off, 12.76 g (0.1 mol) of tellurium powder are added to the filtrate, the resultant mixture is stirred at 20° for 3 h, and then filtered. The solvent is evaporated from the filtrate under reduced pressure and the residue is rccrystallized from dry acetone yield 10.6 g (50%). 

Aryltelluroformates (533), accessible from the corresponding chloroformates, undergo cleavage of the acyl-tellurium bond on photolysis. In the presence of diphenyldiselenide, the oxyacyl radical (534) is trapped as the corresponding alkyl (phenylseleno)formate (535) in excellent yield. Irradiation of aryl bromides or iodides (536) with potassium tellurocyanate (537) in dimethyl sulfoxide, as both solvent and methyl source, yields aryl methyltellurides (538) in modest yields (9-34%). ... 

Tetraethylammonium tellurocyanate has been prepared and the electrochemical oxidation of the TeCN anion in acetonitrile studied. The reaction takes place with the transitory formation of the [(TeCN)3] complex ion, which then gives the unstable (TeCN)2 dimer this in turn decomposes into tellurium and cyanogen. Extending the earlier preparation and spectral study of several tetra-halogenoaryltellurates(iv) ArTeX, the ammonium, sulphonium, selenonium, arsonium, and iodonium derivatives have been prepared, thus giving more complete spectral data. ... 

Tellurium.— The hydrolysis of tellurium hexafluoride has been shown to involve TeF4(OH)a, TeFa(OH)3, and TeFaCOH) as intermediate species. Hydrolysis to Te(OH)e is very slow. The reactivity of the tellurocyanate ion as a nucleophile towards benzyl bromide in acetonitrile has been compared with that of selenocyanate and thiocyanate. The kinetics are second order in each case, and values in mol-i dm s-i at 21 °C are NCTe" 1.20, NCSe- 0.195, and NCS- 0.00324 polarizability appears to be an important factor. 

PhCHzCI + [KTeCN] — PhCH2TeCN A mixture of ground tellurium and KCN in dry dimethyl sulfoxide stirred and heated ca. 1 hr. at 100°, the resulting soln. cooled to room temp., dil. with more dry dimethyl sulfoxide, and a soln. of benzyl chloride in the same solvent added dropwise with stirring, which is continued for 2 hrs. benzyl telluro-cyanate. Y 61%. This is the first isolable alkyl tellurocyanate reported. H. K. Spencer, M. V. Lakshmikantham, and M. P. Cava, Am. Soc. 99, 1470 (1977). 

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