Tellurium polytelluride anion

Only species Te 2- with short chains (n = 2-4) are present in polytelluride solutions [57]. Despite this fact many Zintl-type valence precise tellurium dianions of higher nuclearity have been isolated in the solid state in the presence of suitable counter cations. The three general synthetic routes to such polytelluride anions can be summarized with representative examples as follows ... 

The propensity of tellurium to form intermolecular interactions distinguishes its chemical properties from those of sulfur and selenium for which such secondary bonding is virtually nonexistent (see Ref 38 and references therein). By contrast to polysulfides and polyseleiudes, polytelluride anions can exhibit charges that deviate from -2. 

In contrast to the polysulfides and almost all the polyselenides (exception Cs4Sei6 ), a number of polytelluride anions are also known with total negative charges greater than 2, as, for instance, in NaTe with discrete [Tcs]" ions and in 83X022 with polymeric sheet-Uke [Tcg ] ions. These are examples for the striking variety of structural motifs and formula types (x/y = 5/3, 1/1, 2/3, 2/5, 1/3, 1/4, 1/6, 2/13, 1/7 and 3/22) that are known for the alkali metal polytellurides A TCj, and which reflect the propensity of tellurium both to catenate and to participate in hypervalent coordination polyhedra. Whereas discrete anions are observed for xjy > 2/3, polymeric chain and lamellar anionic networks are present in such tellurides when xfy < 2/5. ... 

Dilution with water reverses the reaction, and heating the solution liberates sulfur dioxide. Upon being added to a solution of tellurides, tellurium forms colored polytellurides. Unlike selenium, tellurium is not soluble in aqueous sodium sulfite. This difference offers a method of separating the two elements. Like selenium, tellurium is soluble in hot alkaline solutions except for ammonium hydroxide solutions. Cooling reverses the reaction. Because tellurium forms solutions of anions, Te2-, and cations, Te4+, tellurium films can be deposited on inert electrodes of either sign. 

Tellurium, potassium hydroxide, water, phenylacetylene, a trialkylmethylammonium chloride as phase-transfer catalyst, either tin(IJ) chloride or hydrazine hydrate as reducing agent and toluene as the organic solvent upon heating at approximately 100 for six hours produced Z,Z-bis[2-phenylvinyl ditellurium in low yields. Polytelluride radical anions were postulated as intermediates2 3. 

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