Cyclopentasilanes reactions

All cyclopentasilanes investigated so far have been prepared from deca-phenylcyclopentasilane by deaiylation with triflic acid (triflation) and subsequent reaction of the triflate compounds with lithium halides, potassiiun halides or lithium aluminum hydride. The reaction sequences are symbolized below (Scheme 1, phenyl groups are not shown). 

Reaction of the appropriate diorganodihalosilane with metals gives cyclosilane derivatives such as octaphenylcyclotetrasilane (14), decaphenyl-cyclopentasilane (14), dodecaphenylcyclohexasilane (14), and dodeca-methylcyclohexasilane (14, 49, 50). The above reactions, as well as the... 

The reaction of octaphenylcyclotetrasilane 14, 47) and decaphenyl-cyclopentasilane 14, 58) with lithium gives the corresponding a,cu-dilithio... 

In addition, the cleavage of octaphenylcyclotetrasilane and decaphenyl-cyclopentasilane with lithium in the presence of chlorosilanes has provided access to a variety of polysilane derivatives. Other reactions describing the use of cyclosilanes for the preparation of polysilanes have been thoroughly reviewed 14),... 

All of these reactions depend upon the fact that octaphenylcyclotetrasilane reacts readily with these reagents while decaphenylcyclopentasilane is relatively stable to them. The same type of an intermediate, namely, a poly-silanyllithium compound which can undergo intramolecular cyclization to give the cyclopentasilane (6), is probably produced in each case. 

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