Polytelluride ions

While not true CD, a novel telluriding agent, Te dissolved in an alkaline solution of hydroxymethanesulphinic acid, has been used to convert Cd(OH)2 films to CdTe [21]. While there is some doubt as to the nature of the active telluriding agent, from the description of the preparation process of this reagent— a change in color from deep purple (characteristic of polytelluride ions, TeJ ) to a faint pink (pure Te is colorless but will be colored this way if traces of TeJ are present) as the preparation proceeds—it does appear to contain free teUuride ion. It should be noted that elemental Te can slowly dissolve in concentrated air-free alkaline solutions, with the formation of polytelluride and its characteristic purple color. 

Structurally, the smaller polyselenide and polytelluride ions resemble their polysulfide analogues, e.g. [Teg] has structure... 

The Gillespie-Nyholm rules usually can also be applied to other polyanionic compounds with hypervalent atoms. As an example, some polytellurides are depicted in Fig. 13.6. The Te

[Pg.136]

Polytellurides, Te , - re less straightforward and often form complex units coordinated to metal centres. The isolated ions Te2 and... 

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. ... 

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