- Dehydrocoupling of silanes catalyzed by zirconocene- and titanocene alkyne complexes
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The zirconocene- and titanocene alkyne complexes 1-10 were tested to be effective catalysts in the dehydrocoupling of hydrosilanes like PhMeSiH2 and Ph2SiH2 to give oligomers and of other examples, e.g., PhSiH3
- Peulecke, Normen,Thomas, Dominique,Baumann, Wolfgang,Fischer, Christine,Rosenthal, Uwe
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- First synthesis of the three isomeric parent disilacyclohexanes. An improved preparation of methylene di-grignard
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Ring closure of 1,5-dibromo-1,5-disilapentane with methylene di-Grignard was the key step in the preparation of the parent 1,3-disilacyclohexane. For that purpose, the preparation of methylene di-Grignard has been improved and simplified. The successful s
- Gudnason, Palmar I.,Arnason, Ingvar
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- Si-H bond activation at {(NHC)2Ni0} leading to hydrido silyl and bis(silyl) complexes: A versatile tool for catalytic Si-H/D exchange, acceptorless dehydrogenative coupling of hydrosilanes, and hydrogenation of disilanes to hydrosilanes
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The unique reactivity of the nickel(0) complex [Ni2(iPr 2Im)4(COD)] (1) (iPr2Im = 1,3-di-isopropyl- imidazolin-2-ylidene) towards hydrosilanes in stoichiometric and catalytic reactions is reported. A series of nickel hydrido silyl complexes cis-[Ni(iPr2Im)2(H)(SiHn-1R4-n)] (n = 1, 2) and nickel bis(silyl) complexes cis-[Ni(iPr2Im) 2(SiHn-1R4-n)2] (n = 1, 2, 3) were synthesized by stoichiometric reactions of 1 with hydrosilanes H nSiR4-n, and fully characterized by X-ray diffraction and spectroscopic methods. These hydrido silyl complexes are examples where the full oxidative addition step is hindered. They have, as a result of the remaining Si-H interactions, remarkably short Si-H distances and feature a unique dynamic behavior in solution. Cis-[Ni(iPr2Im)2(H)(SiMePh 2)] (cis-5) shows in solution at room temperature a dynamic site exchange of the NHC ligands, H-D exchange with C6D6 to give the deuteride complex cis-[Ni(iPr2Im)2(D)(SiMePh 2)] (cis-5-D), and at elevated temperatures an irreversible isomerization to trans-[Ni(iPr2Im)2(D)(SiMePh 2)] (trans-5-D). Reactions with sterically less demanding silanes give cis-configured bis(silyl) complexes accompanied by the release of dihydrogen. These complexes display, similarly to the hydrido silyl complexes, interestingly short Si-Si distances. Complex 1 reacts with 4 eq. HSi(OEt) 3, in contrast to all the other silanes used in this study, to give the trans-configured bis(silyl) complex trans-[Ni(iPr2Im) 2Ni(Si(OEt)3)2] (trans-12). The addition of two equivalents of Ph2SiH2 to 1 results, at elevated temperatures, in the formation of the dinuclear complex [{(iPr 2Im)Ni-μ2-(HSiPh2)}2] (6). This diamagnetic, formal Ni(i) complex exhibits a long Ni-Ni bond in the solid state, as established by X-ray diffraction. The capability of the electron rich {Ni(iPr2Im)2} complex fragment to activate Si-H bonds was applied catalytically in the deuteration of Et3Si-H to Et 3Si-D employing C6D6 as a convenient deuterium source. Furthermore, we show that 1 serves as a catalyst for the acceptorless dehydrogenative coupling of Ph2SiH2 to the corresponding disilane Ph2HSi-SiHPh2 and trisilane Ph 2HSi-Si(Ph)2-SiHPh2, and the coupling of PhSiH3 to give a mixture of cyclic and linear polysilanes with high polydispersity (Mw = 1119; Mn = 924; Mw/M n = 1.2). The capability of 1 to catalyze the formal reverse reaction as well is demonstrated by the hydrogenation of disilanes. The hydrogenation of the disilanes Ph2MeSi-SiMePh2 and PhMe 2Si-SiMe2Ph to the corresponding hydrosilanes Ph 2MeSi-H and PhMe2Si-H, respectively, proceeds effectively in the presence of 1 under very mild conditions (room temperature, 1.8 bar H2 pressure).
- Schmidt, David,Zell, Thomas,Schaub, Thomas,Radius, Udo
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- Synthesis of Oligosilanes by Electrolysis of Hydrosilanes
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The novel electrochemical reaction of hydrosilane compounds was investigated for the synthesis of polysilanes.The product obtained by electrolysis of Methylphenylsilane 1a was an oligosilane of Mn=454 (GPC) in 60percent yield, which consisted of Si-Si bonds for the main chain.When diphenylsilane was electrolyzed in a similar manner as 1a, the major product was a dimer in 23percent yield.
- Kimata, Yoshinori,Suzuki, Hiroshi,Satoh, Shin,Kuriyama, Akira
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- Pentamethylcyclopentadienyl-aminoborole derivatives of zirconium and hafnium with alkyl and allyl ligands
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The preparations of new alkyl, iodo, and allyl derivatives of zirconium and hafnium with pentamethylcyclopentadienyl and aminoborole ancillary ligands are described. The dialkyl complexes Cp * {η5-C4H4BN(CHMe2)2}ZrR2Li (R = Me, C≡C-p-C6H4CH3, C≡CMe3, CH2Ph) are prepared from Cp * {η5-C4H4BN(CHMe2)2}ZrCl · LiCl and two equivalents of RLi. Cp * ZrI3 is prepared from Cp * ZrCl3 and BI3. Treatment of Cp * ZrI3 with Li2(THF){C4H4BN(CHMe2)2} yields Cp * (η5-C4H4BN(CHMe2)2}ZrI · LiI(THF). Treatment of Cp * (η5-C4H4BN(CHMe2)2}MCl · LiCl (M = Zr, Hf) with allyl magnesium bromide yields Cp * (η5-C4Me4BN(CHMe2)2}M(η3-C3H5) (M = Zr, Hf). Addition of donor ligands to Cp * (η5-C4H4BN(CHMe2)2}Hf(η3-C3H5) yields Cp * (η5-C4H4BN(CHMe2)2}Hf(η3-C3H5)(L) (L = PMe3, CO) and Cp * (η5-C4H4BN(CHMe2)2}Hf(η1-C3H5)(py). The results of X-ray structure determinations for Cp * (η5-C4H4BN(CHMe2)2}Hf(η3-C3H5) and Cp * (η5-C4H4BN(CHMe2)2}Hf(η3-C3H5)(CO) are reported.
- Pastor, Antonio,Kiely, Andrew F.,Henling, Lawrence M.,Day, Michael W.,Bercaw, John E.
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- Iridium Pincer Catalysts for Silane Dehydrocoupling: Ligand Effects on Selectivity and Activity
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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).
- Mucha, Neil T.,Waterman, Rory
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- Hydrogenolysis of Polysilanes Catalyzed by Low-Valent Nickel Complexes
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The dehydrogenation of organosilanes (RxSiH4?x) under the formation of Si?Si bonds is an intensively investigated process leading to oligo- or polysilanes. The reverse reaction is little studied. To date, the hydrogenolysis of Si?Si bonds requires very harsh conditions and is very unselective, leading to multiple side products. Herein, we describe a new catalytic hydrogenation of oligo- and polysilanes that is highly selective and proceeds under mild conditions. New low-valent nickel hydride complexes are used as catalysts and secondary silanes, RR′SiH2, are obtained as products in high purity.
- Comas-Vives, Aleix,Eiler, Frederik,Grützmacher, Hansj?rg,Pribanic, Bruno,Trincado, Monica,Vogt, Matthias
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supporting information
p. 15603 - 15609
(2020/04/29)
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- Reactivity of the bis(silyl) palladium(II) complex toward organic isothiocyanates
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The bis(silyl) palladium(II) complex [Pd(SiHPh2) 2(dmpe)] (dmpe = 1,2-bis(dimethylphosphino)ethane) reacted with organic isothiocyanates R-NCS (R = Ph, iPr, allyl) to give a dithiocarbonimidato [Pd(S2CN-Ph)(dmpe)] (1), a diphenylsilanedithiolato [Pd(S2SiPh2)(dmpe)] (2), or a π-allyl [(η3-allyl)Pd](NCS) (3) palladium complex, depending on the isothiocyanate type and reaction conditions. In addition, various dithiocarbonimidato Pd(II) complexes were also obtained from trans-[PdEt 2L2] (L = PMe3, PMe2Ph) (4-6) or [Pd(styrene)L2] and organic isothiocyanates.
- Kim, Yong-Joo,Jeon, Hyung-Tak,Lee, Kyung-Eun,Lee, Soon W.
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experimental part
p. 2258 - 2263
(2010/09/08)
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- Investigation of titanium-catalysed dehydrogenative coupling and hydrosilylation of phenylhydrogenosilanes in a one-pot process
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Titanium-catalysed dehydrocondensation and hydrosilylation of primary, secondary and tertiary phenylsilanes have been investigated in a one-pot process with Cp2Ti(OPh)2 as catalyst by NMR studies. Only primary and secondary silanes were found to undergo simultaneous dehydrogenative coupling and hydrosilylation reactions to produce the functional polysilanes.
- Garcia, Julien,Meyer, Daniel J.M.,Guillaneux, Denis,Moreau, Jo?l J.E.,Wong Chi Man, Michel
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experimental part
p. 2427 - 2433
(2009/09/30)
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- Reactivity of group 4 benzamidinate complexes towards mono- and bis-substituted silanes and 1,5-hexadiene
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Zirconium and titanium bis(benzamidinate) dimethyl complexes were found to be active catalytic precursors for the oligomerization of mono- and bis-substituted silanes. The activation of such complexes, by an excess of MAO or by an equimolar amount of B(C
- Volkis, Victoria,Averbuj, Claudia,Eisen, Moris S.
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p. 1940 - 1950
(2007/10/03)
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- Direct construction of silicon-silicon bond by using the low-valent titanium reagent
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The reductive dimerization or polymerization of organochlorosilanes has been achieved by using the low-valent titanium reducing agent other than the alkali metals that are invariable used in the Wurtz-type coupling reaction. Applying this method, the corresponding disilanes or poly(methylvinylsilane) was obtained in good yields. The poly(methylvinylsilane) synthesized by this method is highly pure with a high molecular weight and a narrow molecular weight distribution (Mw/Mn = 1.6, Mn = 16,860).
- Lai, Guoqiao,Li, Zhifang,Huang, Jiabang,Jiang, Jianxiong,Qiu, Huayu,Shen, Yongjia
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p. 3559 - 3562
(2008/02/12)
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- Electrochemical synthesis of symmetrical difunctional disilanes as precursors for organofunctional silanes
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Difunctional disilanes of the general type XR2SiSiR2X (1-5) (X = OMe, H; R = Me, Ph, H) have been synthesized by electrolysis of the appropriate chlorosilanes XR2SiCl in an undivided cell with a constant current supply and in the absence of any complexing agent. Reduction potentials of the chlorosilane starting materials derived from cyclic voltammetry measurements were used to rationalize the results of preparative electrolyses. Organofunctional silanes of the general formula MeO(Me 2)SiC6H4Y (6a-c, 7) were subsequently obtained by the reaction of sym-dimethoxytetramethyldisilane (1) with NaOMe in the presence of p-functional aryl bromides BrC6H4Y (Y = OMe, NEt2, NH2).
- Grogger, Christa,Loidl, Bernhard,Stueger, Harald,Kammel, Thomas,Pachaly, Bernd
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p. 105 - 110
(2007/10/03)
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- Reactivity of rhodium-triflate complexes with diphenylsilane: Evidence for silylene intermediacy in stoichiometric and catalytic reactions
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Addition of Ph2SiH2 to [Rh-(iPr3P) 2(OTf)] (1) yielded the thermally unstable RhIII adduct [Rh(iPr3P)2-(OTf)(H)(SiPh2H)] (2), which decomposed to [Rh(iPr3P)
- Goikhman, Roman,Milstein, David
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p. 2983 - 2988
(2007/10/03)
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Chlorinated and brominated aryltrisilanes ClnSi3Ar8-n and BrnSi3Ar8-n (Ar = phenyl, p-tolyl) as well as tetrasilanes (Ar = phenyl) have been synthesized. In a first step, Ph3SiSiPh2SiPh3, Ph3SiSiClPhSiPh3, p-Tol3SiSiPh2SiPh3, Ph3SiSip-Tol2SiPh3, Cl3SiSiCl2SiPh3 or H(SiPh2)4H have been prepared, and subsequently treated with trifluoromethanesulfonic acid (CF3SO3H), followed by a nucleophilic substitution of the triflate substituent (CF3O2SO) with X- (X = Cl, Br, H). The physical properties of the resulting compounds, which are valuable precursors for the synthesis of aryltrisilanes HnSi3Ar8-n and aryltetrasilanes HnSi4Ar10-n, have been described and their IR and 29Si NMR spectra have been reported.
- Hassler, Karl,Koell, Wolfgang
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p. 135 - 143
(2007/10/03)
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- Reactions of silanes with the binuclear hydride [{Pr12PCH2CH2PPr1 2}Rh]2(μ-H)2. Catalytic deuterium exchange on diphenylsilane and x-ray structure of [{Pr12PCH2CH2PPr1 2}Rh]2(μ-H)(μ-η2-HSiPh2)
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Stoichiometric reactions of diphenylsilane (H2SiPh2) with [(dippe)Rh]2(μ-H)2 (1; dippe = 1,2-bis(diisopropylphosphino)ethane) have produced the new compounds [(dippe)Rh]2(μ-H)(μ-η2-HSiPh2) (2) and [(dippe)Rh]2(μ-SiPh2)2 (3). An X-ray structure determination of 2 indicates the presence of a three-center, two-electron Rh-Si-H interaction. Deuterium exchange and silicon-silicon coupling to give 1,1,2,2-tetraphenyldisilane are both observed for diphenylsilane in the presence of catalytic amounts of 1; the isolated silyl-dihydride complex 2 and the bis(silylene) derivative 3 are likely to be active in these catalytic cycles.
- Fryzuk, Michael D.,Rosenberg, Lisa,Rettig, Steven J.
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p. 2537 - 2539
(2008/10/08)
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- Uebergangsmetall-Silyl-Komplexe XXXIII. Einfluss der Substituenten am Silicium auf Stabilitaet und Zerfallsprodukte von Bissilyl-Komplexen des Palladiums, (R'3P)2Pd(SiR3)2
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Bissilyl complexes of PdII, (R'3P)2Pd(SiR3)2, are stable in the presence of electron-withdrawing silyl groups (e.g.SiCl3) or if the elimination of disilane is prevented by use of suitable chelate ligands.Reaction of cis-L2PdMe2 (L=MePh2P) with H2SiMePh or H2SiPh2 gives the complexes cis-L2Pd(SiHR2)2 (2) that are only detected spectroscpically; they decompose rapidly by cleavage of H2Si2R4.Reaction of L2PdMe2 with H2SiPh2 not only yields the bissilyl complex, but also HSiMePh2; with HSiPh3 only SiMe2Ph2, but no corresponding bissilyl complex is formed.In contrast, the distinctly more stable complex Pd(Ph2PCH2CH2SiMe2)2 is obtained by reaction of L2PdMe2 with Ph2PCH2CH2SiMe2H.Silanes containing chloro substituents (HSiCl3,HSiCl2Me, SiCl4) do not react with L2PdMe2 to give silyl complexes but undergo chloro/methyl exchange instead to give L2PdCl2 and methylated silanes.Trans-L2Pd(SiCl3)2 (4) was prepared by a novel route, viz., reaction of L2PdCl2 with HSiCl3 and KH.On thermolysis of 4 L2PdCl2 is formed in place of Si2Cl6.
- Schubert, Ulrich,Mueller, Christine
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p. 165 - 172
(2007/10/02)
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- Cp2TiPh2-Catalyzed Dehydrogenative Coupling of Polyhydromonosilanes
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The Cp2TiPh2-catalyzed reaction of dihydrosilanes afforded dehydrogenative coupling products, disilanes and/or trisilanes.The reaction using phenylsilane produced hydride-terminated poly(phenylsilylene) polymers with Mn=730 and Mw=960, which exhibited the longest UV absorption maximum at 245 nm (ε, 5.7x104).
- Nakano, Taichi,Nakamura, Hidehisa,Nagai, Yoichiro
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- HOMOGENEOUS CATALYSIS VIII. CARBENE-TRANSITION-METAL COMPLEXES AS HYDROSILYLATION CATALYSTS
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Some carbene-transition-metal complexes, particularly those of rhodium(I) but also of ruthenium(II), have proved to be effective catalysts for the hydrosilylation (e.g., using SiHEt3 or SiH2Ph2) of ketones (to afford silyl ethers) or alkynes.The addition
- Lappert, Michael F.,Maskell, Robin K.
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p. 217 - 228
(2007/10/02)
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- ORGANIC SONOCHEMISTRY. ULTRASOUND PROMOTED COUPLING OF CHLOROSILANES IN THE PRESENCE OF LITHIUM WIRE
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Triorganometal chlorides, R3MCl (R=alkyl, aryl; M=Si, Sn) are readily coupled to form bimetallics in 42-95percent yields using Li wire and ultrasound.Dihalosilanes give good yields of cyclic polysilanes.
- Boudjouk, Philip,Han, Byung Hee
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p. 3813 - 3814
(2007/10/02)
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