99798-82-0Relevant academic research and scientific papers
Iridium Pincer Catalysts for Silane Dehydrocoupling: Ligand Effects on Selectivity and Activity
Mucha, Neil T.,Waterman, Rory
supporting information, p. 3865 - 3872 (2015/08/19)
Catalytic reactions of bisphosphinite pincer-ligated iridium compounds p-XR(POCOP)IrHCl (POCOP) [2,6-(R2PO)2C6H3, R = iPr, X = H (1); R = tBu, X = COOMe (2); = H (3); = NMe2 (4)] with primary and secondary silanes have been performed. Complex 1 is primarily a silane redistribution precatalyst, but dehydrocoupling catalysis is observed for sterically demanding silane substrates or with aggressive removal of H2. The bulkier compounds (2-4) are silane dehydrocoupling precatalysts that also undergo competitive redistribution with less hindered substrates. Products generated from reactions utilizing 2-4 include low molecular weight oligosilanes with varying degrees of redistribution present or disilanes when employing more sterically demanding silane substrates. Selectivity for redistribution versus dehydrocoupling depends on the steric and electronic environment of the metal but can also be affected by reaction conditions. (Chemical Equation Presented).
Silanediol hydrogen bonding activation of carbonyl compounds
Tran, Ngon T.,Min, Taewoo,Franz, Annaliese K.
, p. 9897 - 9900 (2011/10/09)
Geo-inspired activation: The first example of silanediols activating amide and aldehyde substrates through hydrogen bonding is described. Both NMR and X-ray co-crystallization studies demonstrate binding modes and affinity, and show that silanediol hydrogen-bonding assemblies can be modulated by the addition of carbonyl compounds. These silanols show catalysis in a Diels-Alder reaction and provide insight into the design of new organocatalysts (see figure). Copyright
Efficient synthesis of substituted diarylsilanes
Gigler, Peter,Herrmann, Wolfgang A.,Kuehn, Fritz E.
experimental part, p. 1431 - 1432 (2010/09/14)
A highly efficient synthesis of substituted diarylsilanes is presented. The treatment of substituted arylbromides with tert-bu-tyllithium in diethyl ether at -78 °C, followed by the addition to dichlorodiethoxysilane at the same temperature, leads to the quantitative formation of diaryldiethoxysilane. Selective substitution of the chlorine atoms allows an aqueous work up in air. Subsequently, the diaryldiethoxysilane is reduced to the corresponding diarylsi-lane by stirring with lithium aluminum hydride in diethyl ether. The product is purified by bulb-to-bulb distillation. This method does not lead to any mono- or tri-substituted products and avoids handling gaseous and explosive dichlorosilane, which is a significant advantage over previously reported procedures. Georg Thieme Verlag Stuttgart.
Base-catalyzed dehydrogenative Si-o coupling of dihydrosilanes: Silylene protection of diols
Grajewska, Agnieszka,Oestreich, Martin
supporting information; experimental part, p. 2482 - 2484 (2010/11/18)
The direct dehydrogenative coupling of 1,3- and 1,4-diols and dihydrosilanes is efficiently catalyzed by CsO(10 mol%), cleanly affording six- and seven-membered 1,3-dioxo-2-silacycles with dihydrogen as the sole by-product. Conversely, 1,2-diols do not yield the expected 1,3-dioxo-2- silacyclopentanes, essentially forming cyclic disiloxanes instead. Aside from the synthetic convenience, the procedure itself is also useful for straight-forward diol derivatization prior to GLC analysis. Georg Thieme Verlag Stuttgart · New York.
Reactions of cationic PNP-supported iridium silylene complexes with polar organic substrates
Calimano, Elisa,Tilley, T. Don
experimental part, p. 1680 - 1692 (2010/06/13)
Reactions of PNP-supported silylene complexes [(PNP)(H)Ir-SiRR′] [B(C6F5)4] (R = R′ = Ph (1) and R = H, R′ = Mes (2)) with Lewis bases, carbonyl compounds, alcohols, and amines were investigated. Addition of DMAP (4-dimethylaminopyridine) to 1 and 2 produced base-stabilized silylene complexes [(PNP)(H)IrSiRR′(DMAP)] [B(C6F5)4] (R = R′ = Ph (3) and R = H, R′ = Mes (4)). Reactions of 2 with benzophenone and benzaldehyde afforded the products of stoichiometric hydrosilylation, heteroatom-substituted silylene complexes [(PNP)(H)Ir-SiMes(OCH(Ph)(R))][B(C6F5) 4] (R = Ph (5) and R = H (6)). Complex 1 reacted with DMF or benzophenone, and 2 reacted with DMF, to afford base-stabilized silylene complexes of the type [(PNP)(H)IrSiRR′(B)][B(C6F 5)4] (R = H, R′ = Mes, B = DMF (7); R = R′ = Ph, B = DMF (8) and O-CPh2 (9)). In contrast, treatment of 1 with acetophenone afforded {(PNPH)IrH[SiPh2(OC(-CH2)Ph)]} [B(C6F5)4] (10), from activation of a C-H bond at the α-carbon position of acetophenone. Reactions of alcohols and amines with 1 afforded [(PNPH)IrH(SiPh2OR)][B(C6F 5)4] (R = 3,5-tBu2C 6H3 (11), R = Ph (12), R = iPr (13), and R = tBu (14)) and [(PNPH)IrH(SiPh2NHR)][B(C6F 5)4] (R = Ph (15), R = 3,5-(CF3) 2C6H3 (16)). Exploration of the catalytic activity of iridium silylene complexes with these organic substrates demonstrated that 1 is an effective catalyst for silane alcoholysis and aminolysis and for the hydrosilylation of ketones.
Alkene hydrosilation by a cationic hydrogen-substituted iridium silylene complex
Calimano, Elisa,Tilley, T. Don
supporting information; body text, p. 9226 - 9227 (2009/02/02)
A cationic hydrogen-substituted iridium silylene complex [(PNP)(H)Ir=Si(Mes)H][B(C6F5)4] (2) was synthesized via hydride abstraction from the corresponding neutral iridium silyl hydride complex. DFT calculations for 2 indicate that the cationic charge is localized at the silicon center and depict a LUMO with predominant silicon p-orbital character. Notably, complex 2 reacts rapidly with unhindered alkenes at ambient temperatures to afford disubstituted silylene complexes via Si-C bond formation. Complex 2 is also the catalyst for alkene hydrosilation of primary silanes with a high degree of anti-Markovnikov selectivity. Copyright
The electrochemistry of tetramesityldisilene, Mes2Si=SiMes2
Zhang, Zeng-Rong,Becker, James Y.,West, Robert C.
, p. 2719 - 2720 (2007/10/03)
The outcome of the controlled potential oxidation and reduction of a disilene, tetramesityldisilene (TMDS), indicates that the main silicon containing products involve only one silicon atom and have the general structure Mes2SiX(Y), X and Y being H, OH or F.
Synthesis, structure and photoluminescence of 1,2-disila-acenaphthene Si2C10H10 and 1,2-diaryldisilane reference compounds
Soeldner, Marcus,Sandor, Mario,Schier, Annette,Schmidbaur, Hubert
, p. 1671 - 1676 (2007/10/03)
For the synthesis of the diaryldisilanes Ar-SiH2SiH2-Ar (la, Ar = phenyl; Ib, Ar = p-tolyl; le, Ar = mesityl; Id, Ar = p-anisyl) two convenient preparative routes are reported. The crystal structures of le and Id have been determined in Xray diffraction studies; the disilanes have a staggered transconformation with a crystallographically imposed center of inversion. For la-d no photoluminescence phenomena can be observed. 1,2-Disila-acenaphthene (2) is synthesized in acceptable yield by treatment of 1,8-dilithionaphthalene with 1 equivalent of l,2-bis[((trifluoromethyl)sulfonyl)oxy]disilane Tf-SiH2SiH2-Tf. The crystal structure of 2 has also been determined by X-ray diffraction. The molecule has no crystallographically imposed symmetry but closely follows the symmetry elements of point group C2v. Solutions of 2 exhibit intense fluorescence in the near UV region at room temperature. The fluorescence spectra are discussed in comparison with data on acenaphthene and naphthalene. WILEY-VCH Verlag GmbH 1997.
Synthesis and characterization of sterically hindered diarylsilanes containing 2,4,6-trimethylphenyl and 2,4,6-tris( trifluoromethyl) phenyl substituents. X-ray crystal structure of bisfluorosilane
Braddock-Wilking, Janet,Schieser, Matt,Brammer, Lee,Huhmann, Jean,Shaltout, Raef
, p. 89 - 98 (2007/10/02)
Sterically hindered diarylsilanes have been prepared by two synthetic routes.Dimesitylsilane, Mes2SiH2 (1), (Mes = 2,4,6- trimethylphenyl) was synthesized by reaction of mesityl magnesium bromide with HSiCl3 followed by reduction with LiAlH4, or by reaction of mesityl magnesium bromide with (TfO)2SiH2.The mixed diaryl system, MesPhSiH2 (2), was prepared by reaction of (TfO)PhSiH2, with one equivalent of MesMgBr.Diarylsilanes containing the 2,4,6-tris(trifluoromethyl)phenyl substituent, RF, were prepared by reaction of HSiCl3 with 2 equivalents of RFLi to give (RF)2SiHF (3) through a Cl/F halogen exchange.Reduction of 3 with LiAlH4 afforded (RF)2SiH2 (4) which can also be prepared from RFLi and (TfO)2SiH2.All compounds have been characterized by multinuclear NMR, IR, mass spectrometry and chemical analyses.An X-ray crystallographic study of 3 shows that the immediate geometry about silicon is approximately tetrahedral with a C-Si-C angle of 115.8(1)deg.There are unusual intramolecular interactions in 3 with four short Si . . .F contacts with the ortho-CF3 substituents on the aromatic ring which results in an overall tetracapped tetrahedral geometry about silicon.Crystal data for 3 are as follows: monoclinic, P21/c, with a = 9.827(2) Angstroem, b =15.938(3) Angstroem, c =13.239(3) Angstroem, V = 2072.6(8) Angstroem3, Z = 4; and R = 0.0492 (Rw = 0.0535).The short intramolecular Si . . .F contacts are observed in solution for both 3 and 4 by 29Si NMR spectroscopy.Keywords: Silicon; Group 14; Aryl; Mesityl; Crystal structure; Hindered (bulky) ligands
