Tellurium polymeric networks

As discussed in detail in Section 2.4, the pronounced tendency of tellurium to participate in both hypervalent bonding and secondary 5p2 —> 5a interactions can lead to the construction of polymeric telluride networks. 

Aryl tellurium halides, the postulated intermediates, are polymeric substances in which the tellurium atoms are connected by halogen bridges. The polymer network facilitates the migration of aryl groups required by this reaction10. 

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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