Organophosphorus-Tellurium Rings

1 Binary Anions and Cations. The heavy pnictogens in combination with chalcogens form a large variety of anions.Although many of these binary species form oligomers or polymers with layered or framework structures, there are a number of examples of discrete anions with cyclic structures that are formed with large counterions such as tetralkylammonium or tetraarylphosphonium 

Mixed group 15 group 16 polycations are rare and tend to form clusters. For example, the arsenic-chalcogen cations [As3E4] (E = S, Se) have polycyclic structures similar to those of the well-known isovalent species P4S3 and the bismuth-tellurium cation [Bi4Te4] adopts a slightly distorted cubic 

Three- and five-membered rings (AS2S and AS2S3) have also been structurally characterised for the arsenic-sulfur system. The diarsathiiran cyclo-(RAs)2S [R = C(SiMe3)3] is prepared by the addition of sulfur to the diarsene RAs=AsR. The non-planar five-membered ring cyclo-(PhAs)2S3 is obtained, in addition to cyclo-(PhAsS)4, from treatment of phenylarsenic acid with aqueous ammonia and hydrogen sulfide.  

Dillon, F. Mathey and J. F. Nixon, Phosphorus the Carbon Copy, Wiley, New York, 1997. 

Schisler, P. Lonnecke, T. Gelbrich and E. Hey-Hawkins, Dalton Trans., 2004, 2895. 

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