Cyclohexasilanes synthesis

Undecamethylcyclohexasilanylpotassium is a useful starting material for the synthesis of various cyclohexasilane derivatives, as shown in Scheme 14. Reactions affording bicyclic and polycyclic silanes are reviewed in Section V.A. 

If all-iraws-(PhMeSi)6 is reacted with HCI and AICI3, an isomeric mixture of all possible (SiClMe)6 isomers results, which means that the chlorination is accompanied by racemization56. In the course of the chlorination of the permethylated six-membered ring (SiMe2)6, the second substitution occurs only in the 3 and 4 position57 (equation 32). The formed 1,3- and 1,4-dichlorodecamethylcyclohexasilanes can be separated via their hydrolysis products, 1,3-dihydroxydecamethylcyclohexasilane and decamethyl-7-oxa-hexasilanorbornane58. 1,2-Dichlorodecamethylcyclohexasilane is accessible via a stepwise synthesis of the cyclohexasilane skeleton59. 

Summary The use of oligosilyl dianions greatly facilitates the synthesis of cyclohexasilanes with a specific substituent pattern. A number of such conqiounds differently substituted in 1,4-positions are compared according to their stractural data. While almost all cyclohexasilanes studied so far prefer a chair conformation, we find the unusual example of a twist conformation for l,l,4,4-tetrakis(trimefliylsilyl)-octamethyl-cyclohexasilane (2). 

Synthesis and Photoluminescence of Cyclohexasilanes Bearing Siloxy-and Amino Side Groups... 

The increased reactivity of trill ate groups bonded to silicon relative to halogen substituents can also be utilized for the synthesis of multifunctional cyclopolysilane transition metal derivatives, as has recently been shown for 1,3-disubstituted cyclohexasilanes (equation 35). 

Stueger H, Fuerpass G, Renger K, Baumgartner J (2005) Synthesis, structures, and unusual photoluminescence of O- and N-functional cyclohexasilanes. Organometallics 24 6374... 

Chemyavskii AI, Larkin DY, Buzin MI, Chemyavskaya NA (2011) Synthesis of organosihcon polymers with cyclohexasilane fragments in the main chain. Russ Chem Bull 60 304... 

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