Lead-chalcogen rings

The interaction of polycations with free chalcogens leads, in some cases, to new cluster compounds.185 Reaction of the aromatic tetraatomic selenium dication with diphenyldiselenide affords Ph2Se62+ - compound 159 with a six-membered selenium ring (Scheme 66).186... 

U.v.-visible spectral studies indicate that the ligand generally forms a chelate structure (35) with four-membered rings, and that the crystal field of Se is weaker than S. However, nephelauxetic parameters indicate that replacement of S by Se leads to a slight increase in the covalent character of the M-chalcogen bond. Another interesting paper describes the synthesis of the first selenocar-bamato complexes ... 

One of the most interesting properties of chalcogens is the ease with which E—E bonds are broken and reformed, leading to an extraordinary ability to form rings or chains of different lengths." ... 

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