Synthesis, 1H, 13C, and 29Si nuclear magnetic resonance spectra and crystal structure of trans-1,4-diphenyldecamethylcyclohexasilane

Kumar, K.E. Manoj; Litt, Morton H.; Chadha, Raj K.; Drake, John E.

doi:10.1139/v87-074

Cited by 18 publications

(8 citation statements)

References 7 publications

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“…In both structures the cyclohexasilane ring adopts a twist-boat conformation, which is rather unusual, because most cyclohexasilanes studied so far feature a chair conformation of the cyclopolysilane cycle . The geometry around the endocyclic silicon atoms is approximately tetrahedral with Si–Si–Si bond angles close to the respective angles found in other cyclohexasilane structures, ,, although Si(1) exhibits some distortion due to the steric bulk of the attached t -Bu or Ad group.…”

Section: Resultsmentioning

confidence: 77%

Photoinduced Brook-Type Rearrangement of Acylcyclopolysilanes

et al. 2013

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Previously unknown 1,1,4-tris(trimethylsilyl)-4-acyldodecamethylcyclohexasilanes (Me3Si)2Si6Me12(Me3Si)COR (16a, R = tert-butyl; 16b, R = 1-adamantyl) have been synthesized by the reaction of the potassium silanides (Me3Si)2Si6Me12(Me3Si)K with acid chlorides ClCOR, and their photochemical rearrangement reactions have been studied. The molecular structures of 16a,b as determined by single-crystal X-ray diffraction analysis exhibit an unusual twist-boat conformation of the cyclohexasilane ring. When 16a,b were photolyzed with λ >300 nm radiation, they underwent Brook type 1,3-Si → O migration reactions to generate the cyclohexasilanes 17a,b with exocyclic Si=C bonds along with smaller amounts of the ring-enlarged species 19a,b with endocyclic Si=C double bonds. While 17a,b were stable enough to allow characterization by NMR and UV absorption spectroscopy, the less stable products 19a,b could only be observed in the form of their methanol adducts.

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Section: Resultsmentioning

confidence: 77%

Photoinduced Brook-Type Rearrangement of Acylcyclopolysilanes

et al. 2013

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“…Usually, trans -isomers are obtained, as they crystallize much easier. Pure trans -1,4-Ph 2 Si 6 Me 10 can for instance be crystallized from a mixture of many components (in 5% yield) …”

Section: Resultsmentioning

confidence: 99%

“…After workup, 1 H NMR of the product, which was obtained in quantitative yield, showed that it was the cis -isomer that was present in a 2.3-fold excess. Hereto use was made of the 1 H NMR spectrum of trans -1,4-Ph 2 Si 6 Me 10 , of which the identity has previously been established by X-ray diffraction . Thus, in both cases the majority of trans -dichloride is converted into the cis -diaryl-substituted product.…”

Section: Resultsmentioning

confidence: 99%

“…Nevertheless, it can be stated that the cyclohexasilane ring strongly prefers a chair or chairlike geometry since in all 19 cyclohexasilane derivatives recorded in the Cambridge Structural Database this ring geometry is found. Compounds included are, for example, dodecamethylcyclohexasilane, Si 6 Me 12 ; trans -1,4-Ph 2 Si 6 Me 10 ; and 1,3,5-Ph 3 Si 6 Me 9 . Not unexpectedly, the phenyl substituents tend to occupy an equatorial position.…”

Section: Introductionmentioning

confidence: 99%

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Synthesis and Structure of cis-1,4-Di(1-pyrenyl)decamethylcyclohexasilane

et al. 2003

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The synthesis and structure of cis-1,4-di(1-pyrenyl)decamethylcyclohexasilane (2), one of the first cis-1,4-substituted cyclohexasilanes, are reported. This isomer is unexpectedly formed as the major product in the reaction of a mixture of trans-and cis-1,4-dichlorodecamethylcyclohexasilane (4a and 4b, respectively) with 1-pyrenyllithium. Reaction of 4a,b with phenyllithium showed that preferential formation of the cis-product is a general feature of this kind of reaction. According to the X-ray crystal structures of two different solvates, the cyclohexasilane ring in 2 adopts a unique boatlike geometry, with the pyrenyl substituents occupying an equatorial or bisectional position. 1 H NMR data indicate that a boatlike geometry also occurs in solution. Furthermore, the X-ray crystal structure of trans-1,4dihydrodecamethylcyclohexasilane, which is an intermediate in the synthetic pathway to 2, is reported.

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“…The structure was determined by X-ray structure determination and NMR data. 246 In an investigation by a Chinese group (p-MeC6H4-SiMe)6, (o-MeC6H4SiMe)6, (PhCH2SiMe)6, (PhEtSi)6, and (PhSiCH2CH:CH2)6 were synthesized by the usual dehalogenation of the dichlorides with Li and characterized by NMR, IR, MS, and UV. 171 In presence of a catalytic amount of sodium methoxide, 1,2-dimethoxytetramethyldisilane was converted into cyclic polysilanes (SiMe2)n (n = 5-7).…”

Section: Nmr Investigationsmentioning

confidence: 99%