Tetrakis silane, reaction

The reaction of halosilanes with alcohols proceeds analogously. Dihinctional amines react with tetrahalosilanes to yield tetrakis(dialkylamino)silanes. 

Model Networks. Constmction of model networks allows development of quantitative stmcture property relationships and provide the abiUty to test the accuracy of the theories of mbber elasticity (251—254). By definition, model networks have controlled molecular weight between cross-links, controlled cross-link functionahty, and controlled molecular weight distribution of cross-linked chains. Sihcones cross-linked by either condensation or addition reactions are ideally suited for these studies because all of the above parameters can be controlled. A typical condensation-cure model network consists of an a, CO-polydimethylsiloxanediol, tetraethoxysilane (or alkyltrimethoxysilane), and a tin-cure catalyst (255). A typical addition-cure model is composed of a, ffl-vinylpolydimethylsiloxane, tetrakis(dimethylsiloxy)silane, and a platinum-cure catalyst (256—258). 

Finally, reaction of SiCLi. 57 with HMDSO 2 affords 84% tetrakis(trimethyl-silyloxy)silane 140 and 16% hexakis(trimethylsilyloxy)disiloxane 141, both of which might be very interesting silylating agents, e.g., for silicon surfaces [72]. 140 is also obtained in 38% yield on reaction of SiCL. 57 with excess sodium tri-methylsilanolate 96 [73] (Scheme 3.14). 

More recently, Auner s and Schleyer s groups in a joint effort reported the experimental observation of an alkyl-substituted 6-sila-2-norbomyl cation110. The 6,6-Dimethyl-5-neopentyl-6-sila-2-norbomyl cation 41 was prepared by a hydride transfer reaction via the jr-route 111 from a suitable cyclopentenyl silane derivative at room temperature (equation 10). The toluene solution of the tetrakis(pentafluorotetraborate) salt of 41... 

Spirocompound 43 was prepared in low yields (20%) by salt metathesis reaction of tetrakis(lithiomethyl)silane with l,2-dichloro-l,l,2,2-tetramethyl disilane <20000M4223>. 

In this connection the formation of irregular polymers (Si BryH R O H with v +x +y +z = 2 is of interest. As a result of steric hindrance566), such compounds will be formed in the reaction of SiBr4 with t-butyl Grignard compound instead of the expected tetrakis (t-butyl)-silane. 

Reaction of tetravinylsilane (78) with H2PtCl6-6 H20 and trichlorosilane afforded the first generation tetrakis(trichlorosilane) (185), which was treated with vinylmagnesium bromide to produce the corresponding dodecavinylsilane (186). Hydrosilylation of silane... 

Moran et al. 41 attached the Cr(CO)3 moiety to tetrakis(phenylsilane) 32 (prepared by the hydrosilylation of tetraallylsilane with four equivalents of dimethylphenylsilane) by treatment with excess Cr(CO)6 in dibutyl ether—THF at 140 °C affording the air-stable, crystalline tetrakis(chromium carbonyl) dendrimer 33, which was also prepared by reaction of tetraallylsilane with [r76-C6H5Si(Me)2H]Cr(CO)3) (Scheme 8.9). 42a Reaction of the corresponding eight phenyl-terminated analogues afforded the partially metalated silane dendrimer 34 as the major product, even with an excess of Cr(CO)6. 

Summary Mono-, bis-, tris-, and tetrakis(lithiomethyl)silanes were prepared by reductive cleavage of C-S bonds with lithium naphthalenide (LiCioHg) or lithium p,p -di-rbutylbiphenylide (LiDBB) and characterized by the reaction with Bu3SnCl. The poly(lithiomethyl)silanes can be used as new building blocks for in a-position substituted silanes or, for example, silacyclobutanes. 

Bis- and tris(lithiomethyl)silanes were prepared with lithium n hthalenide (LiCioHg) and tetrakis(lithiomethyl)silane (17) with lithium p,p -di-/butylbiphenylide (LiDBB) as electron transfer reagent and characterized by reaction with Bu3SnCl [>95 % overall yield by NMR 42 % to 81 % yield of isolated pure (stannylmethyl)silanes] (Scheme 3 and 4). 

A similar reagent, phenylselenotris(trimethylsilyl)silane (52), reacts with chloroformates in the presence of tetrakis(triphenylphosphine)palladium to produce (phenylseleno)formates 53 (Scheme 40) [79]. This reaction is also applicable to the preparation of selenol esters and selenol thionoformates [79]. 

A remarkable reaction leading to polysilanes in which silicon atoms possess fourfold silicon coordination was pubhshed by Maxka et al. Tetrakis(chlorodi-methylsilyl)silane, which was obtained from SiCl4, Li, HMe2SiCl, and CCI4 was coupled using lithium metal in tetrahydrofuran (THF) solution. [(SiMe2)4Si] was obtained as a waxy orange solid with a yield of approximately 90%. 

A well-established route to tetrakis(4-biphenylyl)silane (233) is the reaction of 4-bromobiphenyl (232) with SiCl4 and sodium (yield 90%) according to Wurtz synthesis (equation 112)141. 

An established pathway to naphthylsilanes is the Grignard reaction which, in this case, requires fluorosilanes as silicon components, as can be shown by the synthesis of bis (l-naphthyl)difluorosilane (234) (equation 113a)131. However, for the synthesis of tetrakis (2-naphthyl)silane (235) it is preferable to use lithiated naphthalene (equation 113b)142. In... 

The reaction of a thiol with tetrachlorosilane yields tetrakis(alkylthio)silanes (759)433 (equation 392). 

The silicon-silicon bond in polysilanes is broken by alcoholic or aqueous alkali (the latter in a cosolvent) with the formation of Si-OR or Si-OH bonds and liberation of dihydrogen. Cleavage of the Si-Si bond by alkali metals is also observed, and was described in Section II.A for perphenylcyclosilanes. An important example is the reaction of tetrakis(trimethylsilyl)silane to give the silyllithium compound 1474 (equation 29). 

A general cyclization reaction of 6-lithiated (trimethylsilyl)alkynes is exemplified by the conversion of the iodo compound 499 into the methylenecyclopentane 500 by treatment with -butyllithium . Heating a mixture of the acetylenic silane 501 and 2-(benzyloxymethyl)allylzinc bromide 502 resulted in the diene 503, which cyclized to the methylenecyclopentene 504 in the presence of tetrakis(triphenylphosphine)palladium ... 

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