Tris cyclotrisilane

Functionalized cyclotrisilane derivatives bearing oxygen- or nitrogen-containing substituents are also known. The synthesis of the aryl-alkoxy cyclotrisilane trimesityl-tris(2,6-diisopropylphenoxy)cyclotrisilane can be easily accomplished by the photolysis of 2-mesityl-2-(2,6-diisopropylphenoxy)-l,l,l,3,3,3-hexamethyltrisilane via several silylene extrusion and addition steps (equation 7)40. 

Hexa-substituted cyclotrisilanes have been shown to be excellent precursors of disilenes. Tetraisopropyldisilene (280), for example, can be obtained by photoextrusion of di-isopropylsilylene (281) from hexaisopropylcyclotrisilane (282). Z- and E-substituted disilenes have similarly been obtained on photodecomposition of tri-t-butyl-trimesitylcyclotrisilanes photochemically induced Z,E-isomerization has been reported in this disilene. ... 

This cyclotrisilane was prepared through the reaction of NajAs with tris(trimethylsilyl)chlorosilane at 0°C in hexane. The carefully chosen experimental conditions led to the isolation of colorless crystals which could be purified by vacuum sublimation and recrystallization in -hexane. 

Obviously, the first step of the reaction of R SiX3 with NaR in THF consists — according to Scheme 1 and Ref. [7] — in an exchange of halogen against sodium. The monoanions formed are metastable at -78 C, but eliminate NaX at about -50 °C with the formation of silylenes R SiX (8), which may then insert into the Si-Na bond of their precursors several times to build a silicon chain. The di-, tri-, or tetrasilanides obtained may transform, by elimination of NaX, into dihalodisilenes R XSi=SiXR (9), cyclotrisilanes (R XSi)3 (10) and cyclotetrasilanes (R XSi)4 (11). 

---