Silicon-, Germanium-, Tin- and Lead-Chalcogen Rings

The majority of the investigations of group 14-group 16 heterocycles have focused on silicon or tin derivatives. Consequently, the emphasis in this section is on these two group 14 elements. 

In contrast to the extensive homologous series known for cyclosiloxanes, monocyclic ring systems of the type (R2SiS) are limited to four- and six-membered rings n = 2, 3). The most common synthetic method involves the reaction of a diorganodichlorosilane with H2S in the presence of a base such as triethylamine or pyridine [eqn (10.34)].  

Cyclic compounds containing Si2E2 rings (10.56, E = S, Se) are also formed from the reaction of a stable silylene with sulfur or selenium [eqn (10.37)]. The reaction of the divalent germanium compound Ge[N(SiMe3)2]2 with 

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