Cyclotrisilanes structures

The photochemical cleavage of Si-Si bonds of cyclotetrasilanes has been reported to generate several reactive intermediates. For example, Nagai and co-workers reported that silylene and cyclotrisilane are generated during the photolysis of a cyclotetrasilane with a folded structure.73 Shizuka, Nagai, West, and co-workers reported that the photolysis of planar cyclotetrasilanes gives two molecules of disilene.74... 

In view of the extensive chemistry of alkenes it wus only natural for organic and inorganic chemists to search for analogous Si=Si doubly bonded structures. For a long time such attempts proved to be fruitless. The first stable C—SiB and Si=Si9 compounds were synthesized about a decade ago. One synthesis involves the rearrangement of cyclotrisilane ... 

The first structurally confirmed [2 + 4] adduct of a disilene and a 1,3-diene was compound 89, obtained from cyclopentadiene and 4174. The formation of the tricyclic compound 95 from furan and the cyclotrisilane 40 is probably initiated by a [2 + 4] cycloaddition of 41 to the five-membered ring to afford 94, which then undergoes a [2 + 1] addition at the newly formed double bond with the silylene 42 formed concomitantly in the photolysis of 40 (equation 16)74. 

Compounds (107 R, R = Me) and (108) transport chloride and bromide ions from one aqueous solution to another. The cyclotrisilane (109), prepared from commercially available 3-chloro-propyltrimethoxysilane in nine steps <88TL297>, was structurally assigned by mass spectrometry and H and C NMR spectroscopy. A solution of (109) in dichloromethane transported chloride or bromide ions from one aqueous solution to another, but not fluoride or iodide ions host-guest complexes of type (110) (Equation (10)) were postulated as intermediates in the transport processes. 

Keywords Hypersilyl / Group 15 Cages / Cyclotrisilane / Crystal Structure... 

Through the reaction of (Na/K)3M (M = P, As, Sb, Bi) with XSi[Si(CH3)3]3 (X= 1, Br, Cl, F, PhS, CF3SO3) we prepared various cyclic M-Si compounds such as the P7 cage. Using suitable conditions these reactions tend to yield unexpected cyclic and cage-like structures through rearrangement, for instance hexakis(trimethylsilyl)cyclotrisilane. 

Fig. 4. Structure of hexakis(trimethylsilyl)cyclotrisilane [Si(SiMe3)2]3-Hypersilylphosphine H2PSi(SiMe3)...

Attempts to prepare hexaphenylcyclotrisilane by reaction of 1,3-dichloro-hexaphenyltrisilane with sodium in refluxii xylene or with magnesium in tetrahydrofuran resulted only in a variety of products, including octaphenylcyclotetrasilane, decaphenylcyclopentasilane, and Compound C. No product so far isolated could be ascribed the structure of the cyclotrisilane, a highly strained ring system. 

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