Multiple Bonds to Silicon (Recent Advances in the Chemistry of Silicon Containing Multiple Bonds)

Baceiredo, Antoine; Kato, Tsuyoshi

doi:10.1016/b978-0-12-801981-8.00009-5

Cited by 19 publications

(9 citation statements)

References 338 publications

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“…The chemical shift of the unsaturated silicon nuclei of 2 (86.3 ppm) was shifted upfield compared to that of the silyl-substituted spiropentasiladiene A (154.0 ppm). Similar upfield shifts of 29 Si NMR resonances caused by alkyl substituents have been reported for acyclic disilenes and cyclotrisilenes. , The UV–vis spectrum of 2 in 3-methylpentane at room temperature exhibits a broad absorption band with four shoulders (391, 351, 307, and 275 nm) and a tail up to 550 nm (Figure S11). Akin to A and B , this characteristic broad absorption band with shoulders is attributed to the transition from the two delocalized π(SiSi) orbitals on the Si 5 skeleton to the two corresponding delocalized π*(SiSi) orbitals…”

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confidence: 95%

“…Synthetic studies on spiropentadienes have shown that the parent spiropentadienes and its monochloride derivative lack thermal stability and only survive below 173 K . However, it is possible to isolate silicon and germanium analogues of spiropentadiene that bear bulky substituents (Figure b) . Spiropentasiladiene A , which exhibits two perpendicular SiSi double bonds, has been isolated as a dark-red crystalline solid …”

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A Spiropentasiladiene Radical Cation: Spin and Positive Charge Delocalization across Two Perpendicular Si═Si Bonds and UV–vis–NIR Absorption in the IR-B Region

et al. 2021

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Spiroconjugation, that is, through-space orbital interactions between two perpendicular π orbitals, is a key concept in the contemporary molecular design of spirocyclic π-electron systems. We synthesized spiropentasiladiene radical cation salt 1 as a dark-green solid via the one-electron oxidation of the stable spiropentasiladiene 2. Characterization of the molecular structure combined with theoretical studies indicated that the spin and positive charge are delocalized across the two perpendicular SiSi double bonds of 1. Two π(SiSi) orbitals are split into HOMO and SOMO with a small energy gap owing to the second-order Jahn–Teller distortion and steric repulsion between bulky alkyl groups upon one-electron oxidation. In the UV–vis–NIR spectrum, the longest-wavelength absorption band of 1 (λmax = 1972 nm) covers the IR-B region (1400–3000 nm; 0.89–0.41 eV) despite having the smallest possible spiroconjugation motif. The unprecedented absorption band in the IR region was assigned to the HOMO → SOMO transition that arises from the delocalized π-orbitals in the spirocyclic Si5 skeleton.

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A Spiropentasiladiene Radical Cation: Spin and Positive Charge Delocalization across Two Perpendicular Si═Si Bonds and UV–vis–NIR Absorption in the IR-B Region

et al. 2021

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“…Also, we could demonstrate the recovery of silyliumylidene A from VIIIa-c by the treatment with AuI as well as chalcogen transfer reactions. For the last 30 years, neutral congeners of VIIIa-c, silanechalcogenones R2Si=E with E = S, Se, Te have been studied extensively [61]. In contrast, related compounds of type RHSi=E (E = S, Se, Te) are limited to the studies on intramolecularly stabilized silathioformamide by Driess and coworkers [50] and the NHC-stabilized heavier silaaldehydes by Müller and coworkers [62].…”

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S–H Bond Activation in Hydrogen Sulfide by NHC-Stabilized Silyliumylidene Ions

et al. 2018

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Reactivity studies of silyliumylidenes remain scarce with only a handful of publications to date. Herein we report the activation of S-H bonds in hydrogen sulfide by mTer-silyliumylidene ion A (mTer = 2,6-Mes 2 -C 6 H 3 , Mes = 2,4,6-Me 3 -C 6 H 2 ) to yield an NHC-stabilized thiosilaaldehyde B. The results of NBO and QTAIM analyses suggest a zwitterionic formulation of the product B as the most appropriate. Detailed mechanistic investigations are performed at the M06-L/6-311+G(d,p)(SMD: acetonitrile/benzene)//M06-L/6-311+G(d,p) level of density functional theory. Several pathways for the formation of thiosilaaldehyde B are examined. The energetically preferred route commences with a stepwise addition of H 2 S to the nucleophilic silicon center. Subsequent NHC dissociation and proton abstraction yields the thiosilaaldehyde in a strongly exergonic reaction. Intermediacy of a chlorosilylene or a thiosilylene is kinetically precluded. With an overall activation barrier of 15 kcal/mol, the resulting mechanistic picture is fully in line with the experimental observation of an instantaneous reaction at sub-zero temperatures.

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“…The synthesis and characterization of multiply bonded silicon compounds have long been of interest because the bonding and chemistry of these compounds differ from those of their carbon analogues. Although a number of doubly bonded silicon species have been reported, compounds with a silicon–silicon triple bond are much less common. In 2004, the groups of Sekiguchi and Wiberg independently reported the first syntheses of disilynes ( A in Chart ) with extremely bulky silyl groups .…”

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“…Anionic silicon species are important intermediates in synthetic chemistry. Many silyl anions have been reported, but multiply bonded anionic silicon species are rare, although their utility for the synthesis of novel silicon double bonds has been demonstrated. , Considering the utility of Grignard reagents, it is surprising that magnesium silyl complexes are much less common. In fact, no stable magnesium complexes of alkyne analogues based on group 14 elements have been isolated.…”

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Isolation of a 1-Magnesium-2,3-disilacyclopropene and a Related Bis(disilenide)

et al. 2020

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Herein we report the first synthesis of a 1-magnesium-2,3-disilacyclopropene and a related bis(disilenide). Reduction of (boryl)tribromosilane (1, boryl = (HCArN)2B, Ar = 2,6-iPr2C6H3) with magnesium in THF afforded boryl-substituted magnesium complex [(boryl)Si]2Mg(THF)3 (2) in good yield, whereas reduction of (boryl)trichlorosilane (3) with KC8 in THF led to the isolation of bridged alkoxy alkyl bis(disilenide) (THF)K(boryl)SiSi(boryl)O(CH2)4(boryl)SiSi(boryl)K(THF) (4) via ring opening of a THF molecule. X-ray diffraction analysis of 2 confirmed the presence of the novel Si2Mg three-membered ring as well as the SiSi double bond, which existed in a noticeably twisted B–Si–Si–B array. Complex 2 also represents the first reported example of a stable disilyne dianion.

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Multiple Bonds to Silicon (Recent Advances in the Chemistry of Silicon Containing Multiple Bonds)

Cited by 19 publications

References 338 publications

A Spiropentasiladiene Radical Cation: Spin and Positive Charge Delocalization across Two Perpendicular Si═Si Bonds and UV–vis–NIR Absorption in the IR-B Region

A Spiropentasiladiene Radical Cation: Spin and Positive Charge Delocalization across Two Perpendicular Si═Si Bonds and UV–vis–NIR Absorption in the IR-B Region

S–H Bond Activation in Hydrogen Sulfide by NHC-Stabilized Silyliumylidene Ions

Isolation of a 1-Magnesium-2,3-disilacyclopropene and a Related Bis(disilenide)

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