Stereochemistry of the reaction of cis,trans,cis-2,4,6,8-tetraisocyanato-2,4,6,8-tetramethylcyclotetrasiloxane with triphenylsilanol and 1,1,3,3-tetraphenyldisiloxane-1,3-diol

Seki, Hiroyasu; Abe, Yoshimoto; Gunji, Takahiro

doi:10.1016/j.jorganchem.2010.10.013

Cited by 22 publications

(23 citation statements)

References 29 publications

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“…However, the spectrum of 3 a exhibits a broad absorption band between 3150 and 3600 cm −1 with a maximum at 3366 cm −1 suggesting the presence of hydrogen bonding of the siloxanediol molecules. Ph 2 Si(OH)(μ‐O)Si(OH)Ph 2 exhibits a comparable absorption band at 3425 cm −1 which has been assigned to intermolecular hydrogen bridges . This observation is in contrast to the spectrum of 3 a in C 6 D 6 , which reveals intramolecular hydrogen bonding for the cis isomer.…”

Section: Resultsmentioning

confidence: 87%

“…Only when the disiloxanes 2 a – 2 c were reacted in [D 8 ]THF with an excess of water at 60 °C for three days, clear solutions were obtained, from which the siloxanediols were separated after work‐up as colorless powders that can be handled under ambient conditions. Remarkably, all attempts to synthesize 3 a by hydrolysis of the dichlorosilane Mes 2 SiCl 2 failed, although Ph 2 SiCl 2 is known to react with water to yield Ph 2 Si(OH)(μ‐O)Si(OH)Ph 2 . In contrast, the formation of 3 a was observed within two hours when 2 a was reacted in C 6 D 6 with an equimolar amount of dihydroxodiphenylsilane Ph 2 Si(OH) 2 in presence of NEt 3 .…”

Section: Resultsmentioning

confidence: 99%

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Reactivity of the Sterically Demanding Siloxanediol Mes₂Si(OH)(μ‐O)Si(OH)Mes₂ Towards Water and Ether Molecules

Roesch

Warzok

Enke

et al. 2017

Chemistry A European J

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A series of isotopologues of the siloxanediol Mes Si(OH)(μ-O)Si(OH)Mes (3 a) (Mes=2,4,6-trimethylphenyl) were synthesized by reactions of the corresponding disiloxane precursors Mes Si(μ-O) SiMes (2 a), Mes Si(μ- O) SiMes (2 b) or Mes Si(μ- O) SiMes (2 c) with an excess of H O, H O or H O. NMR and IR signal assignments for the siloxanediols in benzene are supported by quantum-chemical calculations, which indicate small energy differences between trans and cis conformers, the latter of which exhibits an intramolecular hydrogen bond. H NMR as well as IR data suggest the presence of a mixture of both conformers in C D . Hydrogen-bonded adducts of Mes Si(OH)(μ-O)Si(OH)Mes with ethers such as diethylether, dimethoxyethane or dioxane were observed in the solid state, where they form polymeric chain-like structures. The latter appear to be stable only in the crystal. O{ H} NMR and IR data in THF solution suggest an interaction of 3 a with at least one THF molecule, whereas diethylether appears not to interact. Water adducts form neither in solution nor in the solid state as indicated by NMR and ATR IR data. O{ H} NMR and ESI-MS experiments illustrate the remarkably high stability of the siloxanediols towards water and show no evidence for intra- or intermolecular oxygen-exchange reactions. In marked contrast, a stepwise exchange of all three oxygen atoms-including the one in the Si-O-Si bridge-occurred in the gas phase, when [Mes Si( OH)(μ- O)Si( O)Mes ] was treated with H O in the hexapole of an ESI FT-ICR mass spectrometer. The scrambling between the bridging and the other oxygen atoms likely proceeds through cyclic Si O intermediates.

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Section: Resultsmentioning

confidence: 87%

Section: Resultsmentioning

confidence: 99%

Reactivity of the Sterically Demanding Siloxanediol Mes₂Si(OH)(μ‐O)Si(OH)Mes₂ Towards Water and Ether Molecules

Roesch

Warzok

Enke

et al. 2017

Chemistry A European J

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“…All manipulations were carried out in a glovebox, or by means of Schlenk‐type techniques under a dry argon atmosphere. The ligand 1,1,3,3‐tetraphenylsilan‐1,3‐diol was synthesized according to literature procedures . The reagents 1,3‐dichloro‐1,1,3,3‐tetraphenylsiloxane, TEMPO, and CrCl 2 were purchased from ABCR, whereas CrCl 3 ⋅3 THF was purchased from Sigma–Aldrich and all were used as received.…”

Section: Methodsmentioning

confidence: 99%

“…2019, 25,5743 -5750 www.chemeurj.org ligand 1,1,3,3-tetraphenylsilan-1,3-diol was synthesized according to literature procedures. [26] The reagents 1,3-dichloro-1,1,3,3-tetraphenylsiloxane, TEMPO, and CrCl 2 were purchased from ABCR, whereas CrCl 3 ·3 THF was purchased from Sigma-Aldrich and all were used as received. The substrates 2,6-di-tert-butylphenol and 2,6-dimethylphenol were recrystallized five times prior to use.…”

Section: Generalc Onsiderationsmentioning

confidence: 99%

The Influence of Alkali Metal Ions on the Stability and Reactivity of Chromium(III) Superoxide Moieties Spanned by Siloxide Ligands

Wind

Hoof

Herwig

et al. 2019

Chemistry A European J

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In recent years, it has become clear that the presence of redox‐inactive Lewis acidic metal ions can decisively influence the reactivity of metal–dioxygen moieties that are formed in the course of O2 activation, in molecular complexes, and metalloenzymes. Superoxide species are often formed as the primary intermediates but they are mostly too unstable for a thorough investigation. We report here a series of chromium(III) superoxide complexes [L2Cr]M2O2(THF)y (L=−OSiPh2OSiPh2O−, M+=Li+, Na+, K+ and y=4, 5), which could be accessed, studied spectroscopically and partly crystallized at low temperatures. They only differ in the two incorporated Lewis acidic alkali metal counterions (M+) and it could thus be shown that the nature of M+ determines considerably its interaction with the superoxide ligand. This interaction, in turn, has a significant influence on the stability and reactivity of these complexes towards substrates with OH groups. Furthermore, we show that stability and reactivity are also highly solvent dependent (THF versus nitriles), as donor solvents coordinate to the alkali metal ions and thus also influence their interaction with the superoxide moiety. Altogether, these results provide a comprehensive and detailed picture concerning the correlation between spectroscopic properties, structure, and behavior of such superoxides, that may be exemplary for other systems.

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“…The proposed reaction mechanism is shown in Scheme . The first step involves a nucleophilic attack by pyridine (Pyr) to form a pentacoordinate species, followed by the attack of a second nucleophile Ph 3 SiOH, to afford a hexa‐coordinate intermediate.…”

Section: Resultsmentioning

confidence: 99%

Unusual Reactions of Cyclic Fluorosiloxanes

et al. 2017

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The reactivity of cyclic fluorosiloxanes, all‐cis‐[PhSiOF]4 and [i‐BuSiOF]4, was investigated. Unusual bond cleavage was observed in the reaction of all‐cis‐[PhSiOF]4 with 2,6‐lutidine to afford a hexafluorosilicate salt in 29 % yield. On the other hand, different bond cleavage was observed for [i‐BuSiOF]4 resulting in a formation of a linear fluorotrisiloxane in 50 % yield. All products were characterized by spectroscopic analyses as well as X‐ray crystallography. In this paper, we discuss several new Si–O–Si bond cleavage and formation reactions; all reactions were performed under mild conditions that did not generate harmful acids. Consequently, cyclic fluorosiloxanes could serve as useful precursors for a wide variety of silicon compounds such as linear siloxanes, hexa‐coordinated silicates, and well‐defined silsesquioxanes.

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Stereochemistry of the reaction of cis,trans,cis-2,4,6,8-tetraisocyanato-2,4,6,8-tetramethylcyclotetrasiloxane with triphenylsilanol and 1,1,3,3-tetraphenyldisiloxane-1,3-diol

Cited by 22 publications

References 29 publications

Reactivity of the Sterically Demanding Siloxanediol Mes₂Si(OH)(μ‐O)Si(OH)Mes₂ Towards Water and Ether Molecules

Reactivity of the Sterically Demanding Siloxanediol Mes₂Si(OH)(μ‐O)Si(OH)Mes₂ Towards Water and Ether Molecules

The Influence of Alkali Metal Ions on the Stability and Reactivity of Chromium(III) Superoxide Moieties Spanned by Siloxide Ligands

Unusual Reactions of Cyclic Fluorosiloxanes

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Stereochemistry of the reaction of cis,trans,cis-2,4,6,8-tetraisocyanato-2,4,6,8-tetramethylcyclotetrasiloxane with triphenylsilanol and 1,1,3,3-tetraphenyldisiloxane-1,3-diol

Cited by 22 publications

References 29 publications

Reactivity of the Sterically Demanding Siloxanediol Mes2Si(OH)(μ‐O)Si(OH)Mes2 Towards Water and Ether Molecules

Reactivity of the Sterically Demanding Siloxanediol Mes2Si(OH)(μ‐O)Si(OH)Mes2 Towards Water and Ether Molecules

The Influence of Alkali Metal Ions on the Stability and Reactivity of Chromium(III) Superoxide Moieties Spanned by Siloxide Ligands

Unusual Reactions of Cyclic Fluorosiloxanes

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Reactivity of the Sterically Demanding Siloxanediol Mes₂Si(OH)(μ‐O)Si(OH)Mes₂ Towards Water and Ether Molecules

Reactivity of the Sterically Demanding Siloxanediol Mes₂Si(OH)(μ‐O)Si(OH)Mes₂ Towards Water and Ether Molecules