Cyclic Silanes Research Articles

Schwingungsspektren und Kraftkonstanten von Dodecamethylcyclohexasilan, Decamethylcyclopentasilan und Octamethylcyclotetrasilan sowie ihrer perdeuterierten Derivate

IR- and Raman vibrational spectra of the cyclic silanes (CH 3) 2 n Si n and (CD 3) 2 n Si n ( n = 4, 5, 6) are reported. Selection rules are used to determine the shape of the ring skeletons, indicating that the rings are non-planar. Isotopic shift data are used for the calculation of SiSi- and SiC-stretching force constants.

Gas-phase reactions of cyclic silanes

Gas-phase reactions of cyclic silanes

29Si and 13C NMR spectra of permethylpolysilanes

29Si, 13C and 1H NMR spectra are reported for the series of linear permethylpolysilanes Me(SiMe2)nMe where n = 1 to 6, for the cyclic permethylpolysilanes (Me2Si)n where n = 5 to 8, and for a few related compounds. For linear polysilanes the 29Si and 13C chemical shifts can be accurately calculated from simple additivity relationships based on the number of silicon atoms in α, β, γ and δ positions. Adjacent (α) silicon atoms lead to upfield shifts in the 29Si and 13C resonances, whereas more remote silicon atoms lead to downfield shifts. The 29Si chemical shifts of the polysilane chains are linearly related to the 13C shifts of the carbon atoms attached to the silicon. The 29Si and 13C resonances of the cyclic silanes deviate from this relationship. Ring current effects arising from σ delocalization are suggested as an explanation for the deviations. Proton-coupled 29Si NMR spectra are reported for Me3SiSiMe3 and for (Me2Si)n, n = 5 to 7.

The nmr study and cndo/2 molecular orbital calculation of silacyclobutanes

29Si, 13C and 1H chemical shifts have been determined for twenty-four substituted silacyclobutanes. Coupling constants, 1 J(SiC), for directly-bonded silicon and carbon atoms have been measured. Six substituted silacyclopentanes have been also studied for comparison with the strained 4-membered cyclic compounds. Molecular orbital calculations for cyclic silanes have been carried out using the CNDO/2 method. Net atomic charges, bond-order and other quantum chemical parameters have been obtained from SP- and SPD-basis set computations. Only for the SPD calculation was generally good agreement obtained between experimental data and computed values. The effect of substitution in silacyclobutanes on the chemical shifts and coupling constants is compared to that for silacyclopentanes and acyclic silanes. The unusual trend in the screening of Si nuclei and the sensitivity of C3 to substitution on the Si atom in the silacyclobutanes are explained by the existence of a strong 1-3 transannular interaction, which is confirmed by the measurements of 2 J(SiC 3) and by the computed resonance energies- E R AB.

Addition of some unsymmetrical electrophilic reagents to cyclic αβ-unsaturated silanes

Additions of some iodine based electrophilic reagents to 1-trimethylsilylcyclohexene (1), and its 4-t-butyl derivative, occur with high regio- and stereoselectivity to give adducts in which iodine is attached to C-1 (2 and 5): these adducts have been transformed into a number of functionalised silanes.

Combination band studies of some cyclic silanes

The vapor-phase mid-infrared spectra of six cyclic molecules were investigated using long path lengths and high vapor pressures. Eight different sum and difference bands resulting from the combination of the ring-puckering vibration with a higher frequency fundamental were observed for these molecules. No combination bands were found for silacyclopent-2-ene of 1,1-difluoro-1-silacyclobutane. For a planar molecule such as silacyclopent-3-ene the analysis of the bands is straightforward. For nonplanar silacyclobutane the spectrum is complex and unexplained doublets and extra bands occur. In general, the ring-puckering energy levels in the excited state of another vibration were found to differ little from those in the ground state for the vibrations studied.

Cyclic Organosilicon Compounds. I. Preparation of Cyclic Silanes

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTCyclic Organosilicon Compounds. I. Preparation of Cyclic SilanesRobert WestCite this: J. Am. Chem. Soc. 1954, 76, 23, 6012–6014Publication Date (Print):December 1, 1954Publication History Published online1 May 2002Published inissue 1 December 1954https://doi.org/10.1021/ja01652a035RIGHTS & PERMISSIONSArticle Views634Altmetric-Citations84LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (396 KB) Get e-Alerts Get e-Alerts