- Catalytic Silylation of Dinitrogen with a Dicobalt Complex
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A dicobalt complex catalyzes N2 silylation with Me3SiCl and KC8 under 1 atm N2 at ambient temperature. Tris(trimethylsilyl)amine is formed with an initial turnover rate of 1 N(TMS)3/min, ultimately reaching a turnover number of ～200. The dicobalt species features a metal-metal interaction, which we postulate is important to its function. Although N2 functionalization occurs at a single cobalt site, the second cobalt center modifies the electronics at the active site. Density functional calculations reveal that the Co-Co interaction evolves during the catalytic cycle: weakening upon N2 binding, breaking with silylation of the metal-bound N2 and reforming with expulsion of [N2(SiMe3)3]-.
- Siedschlag, Randall B.,Bernales, Varinia,Vogiatzis, Konstantinos D.,Planas, Nora,Clouston, Laura J.,Bill, Eckhard,Gagliardi, Laura,Lu, Connie C.
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- Some Aspects of Chemistry of the N->Si Chelated Aryloxydihydrosilanes R(ArO)SiH2(R = Ph, ArO) and of the 2,2-Diaryloxytrisilane (Me3Si)2Si(OAr)2{ArO = 2,4,6-[(CH3)2NCH2]3C6H2O}
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Reactions of the pentacoordinate aryldioxydihydrosilane Ph(Ar)SiH2 (1) with hydroxyl groups, carbonyl derivatives and PCl5 resulted in formation of new alcoxylated, phenoxylated and halogenated hydrosilanes Ph(ArO)(H)X (X = Cl, OR, OAr, OC(O)R), respectively. Treatment of the hexacoordinated (4+2) diaryloxydihydrosilane (ArO)2SiH2 (2) with N-chloro- or N-bromosuccinimide, trimethylsilyltriflate or iodine yielded the novel stable silicenium ion [(ArO)2(H)Si](1+)X(1-). Reactions of 2 with sulfur S8 and the transition metal complex Fe(CO)5 have resulted in the isolation of the new complexes (ArO)2Si = E [E = S, Fe(CO)4]. Decomposition modes of the tetracoordinate 2,2-diaryloxytrisilane (Me3Si)2Si(OAr)2 (3) on thermolysis and photolysis have also been studied; two pathways involving formation of the two silylenes (ArO)(Me3Si): and (ArO)2Si: have been identified by trapping experiments
- Ahdab, Aman Akkari-El,Rima, Ghassoub,Gornitzka, Heinz,Barrau, Jacques
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- L'electrosynthese, une voie simple d'acces aux di- et polysilanes
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Electrochemical reduction of chlorosilanes, at constant current intensity, in a single compartment cell fitted with a sacrificial aluminium anode, is a practical and convenient route to di-, tri-, and poly-silanes.
- Biran, C.,Bordeau, M.,Pons, P.,Leger, M.-P.,Dunogues, J.
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- Ultrasound in organometallic chemistry. The effects of temperature, metal purity and power source on the ultrasound-promoted reaction between trimethylchlorosilane and lithium
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The temperature, lithium purity, and the source of ultrasound (bath or probe) all have significant effect on the ultrasound-promoted reaction between Me3SiCl and Li to give Me3SiSiMe3.
- Lickiss, Paul D.,Lucas, Ronan
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- Multiple-bond metathesis mediated by sterically pressured uranium complexes
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(Figure Presented) Completing a circle of reactions: Reaction of a U V-imido complex (2) with a π acid (e.g., CH3NC) affords a UIV-heterocumulene complex (3), which reacts with an alkyl halide to yield the free carbodiimide and corresponding UIV-halide complex (4). Reduction of complex 4 recovers 1, thereby closing a cycle in which a nitrogen atom is transferred from a UV-imido complex to a π acid by multiple-bond metathesis.
- Castro-Rodriguez, Ingrid,Nakai, Hidetaka,Meyer, Karsten
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- Molybdenum-catalyzed transformation of molecular dinitrogen into silylamine: Experimental and DFT study on the remarkable role of ferrocenyldiphosphine ligands
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A molybdenum-dinitrogen complex bearing two ancillary ferrocenyldiphosphine ligands, trans-[Mo(N2)2(depf)2] (depf = 1,1′-bis(diethylphosphino)ferrocene), catalyzes the conversion of molecular dinitrogen (N2) into silylamine (N(SiMe3) 3), which can be readily converted into NH3 by acid treatment. The conversion has been achieved in the presence of Me 3SiCl and Na at room temperature with a turnover number (TON) of 226 for the N(SiMe3)3 generation for 200 h. This TON is significantly improved relative to those ever reported by Hidai's group for mononuclear molybdenum complexes having monophosphine coligands [J. Am. Chem. Soc.1989, 111, 1939]. Density functional theory (DFT) calculations have been performed to figure out the mechanism of the catalytic N2 conversion. On the basis of some pieces of experimental information, SiMe3 radical is assumed to serve as an active species in the catalytic cycle. Calculated results also support that SiMe3 radical is capable of working as an active species. The formation of five-coordinate intermediates, in which one of the N2 ligands or one of the Mo-P bonds is dissociated, is essential in an early stage of the N2 conversion. The SiMe 3 addition to a "hydrazido(2-)" intermediate having the NN(SiMe3)2 group will give a "hydrazido(1-)" intermediate having the (Me3Si)NN(SiMe3)2 group rather than a pair of a nitrido (-N) intermediate and N(SiMe3) 3. The N(SiMe3)3 generation would not occur at the Mo center but proceed after the (Me3Si)NN(SiMe3) 2 group is released from the Mo center. The flexibility of the Mo-P bond between Mo and depf would play a vital role in the high catalysis of the Mo-Fe complex.
- Tanaka, Hiromasa,Sasada, Akira,Kouno, Tomohisa,Yuki, Masahiro,Miyake, Yoshihiro,Nakanishi, Haruyuki,Nishibayashi, Yoshiaki,Yoshizawa, Kazunari
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- 1: 2-Adducts from Silylenes and 1,3-butadiene
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Photochemical generation of dimethylsilylene, methyl(phenyl)silylene and diphenylsilylene in the presence of high concentrations of 1,3-butadiene leads to the formation of 1-sila-3,4-divinylcyclopentanes as major products in addition to the anticipated 1-silacyclopent-3- enes.Also obtained are the ene-reaction products from the silenes, formed by formal 1,3-silyl shifts in the bis(trimethylsilyl)arylsilanes that are employed as the photochemical precursors of MePhSi: and Ph2Si:.Evidence is presented that both the divinylsilacyclopentanes and the silacyclopent-3-enes arise from vinylsilirane intermediates that can be trapped by acetone, yielding stable 3,3-dimethyl-4-vinyl-1- sila-2-oxolanes.Keywords: Silicon; Silylene
- Bobbitt, Kevin L.,Gaspar, Peter P.
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- Facile Synthesis of the Dicyanophosphide Anion via Electrochemical Activation of White Phosphorus: An Avenue to Organophosphorus Compounds
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Organophosphorus compounds (OPCs) have gained tremendous interest in the past decades due to their wide applications ranging from synthetic chemistry to materials and biological sciences. We describe herein a practical and versatile approach for the trans
- Liu, Liu Leo,Mei, Yanbo,Yan, Zeen
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supporting information
p. 1517 - 1522
(2022/02/01)
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- Attenuation of Ni(0) Decomposition: Mechanistic Insights into AgF-Assisted Nickel-Mediated Silylation
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In nickel-mediated Kumada cross-coupling reactions, low valent active nickel complexes are often generated in situ and the ligands usually govern the reactivity or stability of these complexes. However, the decomposition of active nickel complexes is inev
- Balakrishnan, Venkadesh,Chindan, Bincy,Murugesan, Vetrivelan,Rasappan, Ramesh
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supporting information
p. 1438 - 1446
(2022/01/27)
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- Method for preparing hexamethyl disilane
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The invention discloses a method for preparing hexamethyl disilane. The method is characterized in that trimethylchlorosilane is treated as a raw material and reacts in a solvent under the effect of acomposite reducing agent, and NaX or KX is treated as a catalyst in the reaction; after reaction, the product is subject to post-treatment to obtain hexamethyl disilane; X is F, CI, Br, or I; the composite reducing agent is the combination of phosphorus and a metal reducing agent. According to the method, trimethylchlorosilane is treated as the raw material and is subject to reducing coupling reaction with the metal reducing agent and the nonmetallic phosphorus in the solvent. The hexamethyl disilane prepared according to the method has the advantages of being high in economic efficiency, high in yield, small in pollution, and simple to operate; the phosphorus is mixed with the metal reducing agent in the experiment, and the reaction condition is mild, and the safety is high; the yield isup to 85-95%.
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Paragraph 0018-0037
(2019/07/04)
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- Synthesis method of hexamethyl disilane
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The invention discloses a synthesis method of hexamethyl disilane and relates to a chemical process. The synthesis method includes: at the absence of oxygen, heating and stirring the inside of a reaction kettle added with xylene, crown ether and metal sodium, and dropwise adding trimethyl chlorosilane into the reaction kettle; after finishing, controlling temperature in the reaction kettle, holding the temperature, dropwise adding water into the reaction kettle when the temperature in the reaction kettle is lowered to 50+/-5 DEG C, and standing for layering; distilling for dehydration throughan oil-water separator to obtain a crude product-hexamethyl disilane. With the participation of the crown ether, metal sodium is used to react with trimethyl chlorosilane, so that electric potential of metal sodium is changed, activity of metal sodium is improved, and yield of the crude product can reach 73.17%. The synthesis method is simple and easy to control and convenient for industrial production.
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Paragraph 0013-0028
(2018/03/01)
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- Synthesis of an [(NHC)2Pd(SiMe3)2] complex and catalytic cis-bis(silyl)ations of alkynes with unactivated disilanes
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The novel complex cis-[(ITMe)2Pd(SiMe3)2 (ITMe=1,3,4,5-tetramethylimidazol-2-ylidene) has been synthesized by mild oxidative cleavage of Me3SiSiMe3 using [(ITMe)2Pd0]. The use of this complex as precatalyst for the cis-bis(silyl)ation of alkynes using unactivated disilanes is reported. Double the Si: The novel complex cis-[(ITMe)2Pd(SiMe3)2] (1, ITMe=1,3,4,5-tetramethylimidazol-2-ylidene) has been synthesized by mild oxidative cleavage of Me3SiSiMe3 using [(ITMe)2Pd0]. The synthesized complex was used as a precatalyst for the cis-bis(silyl)ation of alkynes using unactivated disilanes.
- Ansell, Melvyn B.,Roberts, Debbie E.,Cloke, F. Geoffrey N.,Navarro, Oscar,Spencer, John
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supporting information
p. 5579 - 5582
(2015/09/21)
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- Reactions of a Zn(i) complex with group 14 azides-formation of zinc azide and zinc hexazene complexes
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Two zinc hexazene complexes L2Zn2(μ-1,6-R 2-N6) (L = HC[C(Me)N(2,4,6-Me3C 6H2)]2; R = Ph (3), Dipp = 2,6-i-Pr 2C6H3 (4)), were synthesized by reaction of the Zn(i) complex L2Zn2 (1) with phenyl azide and 2,6-diisopropylphenyl azide, respectively. 3 represents the second structurally characterized transition metal hexazene complex. In contrast, reactions of 1 with Me3MN3 (M = Si, Sn) yielded the azido complex [LZn(μ-N3)]2 (2) and Me3M-MMe3.
- Gondzik,Schulz,Blaeser,Woelper,Haack,Jansen
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supporting information
p. 927 - 929
(2014/01/06)
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- Reactions of molybdenum hydrides with organochlorosilanes: Silicon-silicon bond formation under mild conditions
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Reactions of molybdenum hydrides containing polydentate phosphinoalkylsilyl ligands with a number of chlorosilanes have been investigated; this has led to the discovery of a novel type of a dechlorinative Si-Si coupling reaction.
- Asaeda, Takahiro,Lee, Joo Yeon,Watanabe, Kyosuke,Minato, Makoto
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p. 1005 - 1007
(2014/07/22)
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- Zwitterionic base-stabilized digermadistannacyclobutadiene and tetragermacyclobutadiene
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The syntheses of a zwitterionic base-stabilized digermadistannacyclobutadiene and tetragermacyclobutadiene supported by amidinates and low-valent germanium amidinate substituents are described. The reaction of the amidinate GeI dimer, [LGe:]2 (1, L=PhC(NtBu)2), with two equivalents of the amidinate tin(II) chloride, [LSnCl] (2), and KC8 in tetrahydrofuran (THF) at room temperature afforded a mixture of the zwitterionic base-stabilized digermadistannacyclobutadiene, [L2Ge2Sn2L 2] (3; L=LGe:), and the bis(amidinate) tin(II) compound, [L 2Sn:] (4). Compound 3 can also be prepared by the reaction of 1 with [LArSnCl] (5, LAr=tBuC(NAr)2, Ar=2,6-iPr 2C6H3) in THF at room temperature. Moreover, the reaction of 1 with the "onio-substituent transfer" reagent [4-NMe2-C5H4NSiMe3]OTf (8) in THF and 4-(N,N-dimethylamino)pyridine (DMAP) at room temperature afforded a mixture of the zwitterionic base-stabilized tetragermacyclobutadiene, [L 4Ge6] (9), the amidinium triflate, [PhC(NHtBu) 2]OTf (10), and Me3SiSiMe3 (11). X-ray structural data and theoretical studies show conclusively that compounds 3 and 9 have a planar and rhombic charge-separated structure. They are also nonaromatic.
- Yeong, Hui-Xian,Xi, Hong-Wei,Li, Yongxin,Kunnappilly, Sophy Bhasi,Chen, Bozhen,Lau, Kai-Chung,Hirao, Hajime,Lim, Kok Hwa,So, Cheuk-Wai
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p. 14726 - 14731
(2013/11/06)
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- Reaction of vanadocene and vanadocene dichloride with ortho-iodobenzoic acid
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At the interaction of bis (η5-cyclopentadienyl)vanadium with iodobenzoic acid or trimethylsilyl o-iodobenzoate in toluene depending on the ratio of the initial reagents bis(η5-cyclopentadienyl)vanadium(o- iodobenzoate) or η5/su
- Gordetsov,Zimina,Ur'Yash,Moseeva
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p. 299 - 302
(2013/08/15)
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- A study on the haterogeneous reaction of trialkylsilyl chlorides with inorganic salts and monocarboxylates catalysed by PEG400
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The important and useful trialkylsilyl pseudohalides R3SiX, where X=NCS, NCO, N3 or CN and R=methyl or ethyl, and trimethylsilyl monocarboxylates, where X=RCOO, were readily prepared in high yields by nucleophilic substitution of R3SiCl with X ions provided by NaX or KX at room temperature catalysed by PEG400 and zinc iodide. The reactions of trimethylsilyl chloride with some metal oxysalts were also studied for the first time.
- Du, Yun-Fei,Cao, Yu-Qing,Dai, Zhi,Chen, Bao-Hua
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p. 223 - 225
(2007/10/03)
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- Reaction of nitrogen(I) oxide with nitrogen-fixing systems on the basis of lithium, chlorotrimethylsilane, and transition metal compounds
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Reaction of nitrogen(I) oxide with nitrogen-fixing systems Li/Me3SiCl/MCln (MCln = CrCl3, CoCl2, Cp2TiCl2, FeCl3, CuCl2) was studied. In these systems nitro
- Leont'ev,Mironov,Fomicheva,Proskurnina,Zefirov
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p. 905 - 906
(2007/10/03)
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- New bisphenols with silylene fragments: Synthesis and spectra
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A series of bisphenols containing silylene sequences were prepared by condensation of 4-(trimethylsiloxy)phenylmagnesium bromide with αω-dichloropermethylsilanes and studied by fluorescence spectroscopy.
- Pushkarev
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p. 1749 - 1751
(2007/10/03)
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- Homoconjugation in allyl silicon derivatives
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New diallyl derivatives of mono- and disilane were obtained and characterized. Fluorescence, 1H, C, and 29Si NMR, as well as IR and Raman spectroscopy were used to show the presence of intramolecular donor-acceptor β-coupling between the silicon atom and the allyl groups, which is realized directly through space by the homoconjugation mechanism (i.e. direct conjugation between vacant 3d orbitals of the silicon atom and the allyl π bonds, not involving σ orbitals of the allyl methylene groups).
- Osadchev,Pushkarev,Nikitina,Shamanin,Skorokhodov
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p. 1378 - 1382
(2007/10/03)
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- Electroreductive Synthesis of Polysilanes, Polygermanes, and Related Polymers with Magnesium Electrodes
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The electroreduction of alkylaryldichlorosilane carried out with Mg cathode and anode in a single compartment cell gave high molecular weight poly(alkylarylsilane) (Mn = 5200-31000, Mw/Mn = 1.4-1.8) in 5-79% yield. The effects of electrode material, monomer concentration, amount of supplied electricity, and ultrasound were investigated. This electroreductive method was also successfully applied to the synthesis of polygermanes, silane-geramane copolymers, and also poly[p-(disilanylene)phenylenes].
- Kashimura, Shigenori,Ishifune, Manabu,Yamashita, Natsuki,Bu, Hang-Bom,Takebayashi, Masakatsu,Kitajima, Satsuki,Yoshiwara, Daisuke,Kataoka, Yasuki,Nishida, Ryoichi,Kawasaki, Shin-Ichi,Murase, Hiroaki,Shono, Tatsuya
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p. 6615 - 6621
(2007/10/03)
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- The photolytic and hydrolytic lability of sisyl (Si(SiMe3)3) ethers, an alcohol protecting group
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The tris(trimethylsilyl)silyl (sisyl) group is a photolabile protecting group for primary and secondary alcohols. Sisyl (tris(trimethylsilyl)silyl) ethers 2b-11b of a number of primary and secondary alcohols 2a-11a were prepared in yields ranging from 70-97%. The resulting silyl ethers were stable to aqueous bases, Grignard reagents and Wittig reagents as would be expected for bulky alkoxysilanes. They were also stable to selected fluoride salts including CsF. The sisyl ethers could be cleaved using photolysis at 254 nm in under 30 minutes to give the starting alcohols in yields ranging from 62-95%. The photolytic behaviour of sisyl ethers was examined in more detail using 2,3-dimethyl-1,3-butadiene as a silylene trap. The regiochemistry of the oligosilane fragmentation to silylenes was shown to be dependent upon the alkoxy group. The hydrolytic stability of three was compared with the analogous t-butyldimethylsilyl ethers. The relative stability of the two silyl groups can be altered by choice of solvent: in acetic acid/water the ease of hydrolysis followed the order ROSi(SiMe3)3 > ROSiMe2t-Bu; the inverse order was observed in CDCl3 using p-TsOH·H2O. Pseudo-first-order rate constants for the acidic hydrolysis of primary, benzylic, and secondary sisyl ether in AcOH/THF/H2O were determined to be 3.74 x 10-2 s-1, 1.94 x 10-2 s-1, and 1.30 x 10-2 s-1, respectively. The analogous rate constants for the TBS ethers were determined to be 6.04 x 10-3 s-1, 3.53 x 10-3 s-1, and 3.49 x 10-3 s-1, respectively.
- Brook,Balduzzi,Mohamed,Gottardo
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p. 10027 - 10040
(2007/10/03)
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- Synthesis, properties, and reactivity of the stilbene complex of ytterbium (PhCH=CHPh)Yb(THF)2. Crystal structure of (2,4,6-But3C6H2O) 2Yb(THF)3
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The stilbene complex of ytterbium (PhCH=CHPh)Yb(THF)2 (1) was prepared by the reaction of YbI2(THF)2 with a twofold excess of (PhCH=CHPh)-+ Li+. Based on the data of IR and ESR spectroscopy and on the results of magnetic measurements, compound 1 was characterized as a complex of divalent ytterbium with the stilbene dianion. The reactivity of complex 1 toward different types of reagents was studied. The structure of the product of the reaction of 1 with 2,4,6-tri(tert-butyl)phenol (2,4,6-But3C6H2O) 2Yb(THF)3 was established by X-ray diffraction analysis.
- Trifonov,Kirillov,Fedorova,Makarenko,Bochkarev,Schumann,Muehle
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p. 2274 - 2279
(2007/10/03)
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- Base catalysed hydrogenation of methylbromooligosilanes with trialkylstannanes, identification of the first methylbromohydrogenoligosilanes
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The Lewis base catalysed hydrogenation of methylchlorooligsilanes with trialkylstannanes can also be applied to the hydrogenation of methylbromooligosilanes. In this way methylbromohydrogenoligosilanes were prepared for the first time. Methylbromotrisilanes with an > SiBrMe middle group (e.g. SiBrMe2-SiBrMe-SiBrMe2) are hydrogenated First at this silicon atom under formation of an > SiHMe group (e.g. SiBrMe2-SiHMe-SiBrMe2). Brominated silanes containing a quarternary Si(Si)4 unit (e.g. Si(SiBrMe2)4) do not react with trialkylstannanes.
- Herzog,Roewer
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p. 117 - 124
(2007/10/03)
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- Mercury-sensitized photolysis of Me2SiH2 the disproportionation reactions of the Me2SiH radical
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Mercury-sensitized photolysis of Me2SiH2 yields in the primary step an Me2HSi radical and an H atom with a quantum yield of one. The Me2HSi radicals undergo a combination reaction [k(2)] as well as two kinds of disproportionate reactions leading to dimethylsilylene [k(3)] and 1-methylsilaethene [k(4)]. The following branching ratios have been determined: k(3)/[k(2) + k(3) + k(4)] = 0.64 ± 0.10 and k(4)/[k(2) + k(3) + k(4)] ≥ 0.007. For Me3Si radicals the branching ratio for disproportionation was also determined and a value of 0.063 was obtained.
- Kerst,Potzinger
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p. 1071 - 1078
(2007/10/03)
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- 2-Selenophenethiol and 5-methylthio-2-selenophenethiol: Synthesis and autoconversions
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Selenophenethiols have been synthesized by a modified organolithium method. The structures of the products were established by their autothiylation and reaction with phenylhydrazine. 1997 Plenum Publishing Corporation.
- Vvedenskii,Shtefan,Malyushenko,Shilkin
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p. 426 - 428
(2007/10/03)
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- Method for introducing hydrocarbons into chlorosilanes
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By reacting a chloromonosilane or chlorodisilane with a halogenated hydrocarbon in a liquid phase in the presence of metallic aluminum or an aluminum alloy, a hydrocarbon group is substituted for at least one chlorine atom of the chlorosilane for introducing hydrocarbon into the chlorosilane. Silanes having a high degree of hydrocarbon substitution can be easily synthesized from chlorosilanes under moderate conditions and with high volumetric efficiency. The reagents used are aluminum or aluminum alloys and halogenated hydrocarbons which are inexpensive and readily available.
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- Method for producing disilanes
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A method for producing disilane characterized in that halosilane is subjected to electrochemical reaction using Al, Al alloy, Mg, Mg alloy, Cu, Cu alloy, Zn or Zn alloy as anode, a lithium salt as supporting electrolyte, an Al salt, Fe salt, Mg salt, Zn salt, Sn salt, Co salt, Pd salt, V salt, Cu salt, Ca salt, Na salt or K salt as current carrying aid, and an aprotic solvent as solvent, thereby producing disilane.
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- Electrochemical Formation of Dimeric Organostannyl Compounds
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Organosilyl stannanes were formed by electroreduction of the corresponding organostannyl chlorides or distannanes with silyl chlorides.The Sn-C bond formation was also confirmed in the reduction of a mixture of stannyl and alkyl chlorides.
- Ishiwata, Toyoaki,Nonaka, Tsutomu,Umezawa, Masanobu
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p. 1631 - 1634
(2007/10/02)
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- Peculiarities in the cleavage by methyllithium of unsymmetrical disilanes
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The title reactions did not produce the more stable silyl anions from the disilanes studied, they either occurred by attack at the more electrophilic silicon atom, or led to unexpected products.
- Hevesi,Dehon
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p. 8031 - 8032
(2007/10/02)
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- The synthesis of -substituted dialkyldichlorosilanes and their conversion into polysiloxanes
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Attack of the oxyl (CF3)2NO. (1) on an ethyl group of the silane Et2SiCl2 occurs at both the α- and β-positions relative to silicon (ratio 31:45), whereas with the silane PrnSiMeCl2 attack takes place at the β-position of the propyl group.With the disilane Me3SiCH2SiMe3, the mojor silicon-containing products formed from treatment with oxyl 1 are Me3SiF, (CF3)2NOSiMe3 and Me3SiSiMe3.Speier-catalysed (H2PtCl6) addition of the silane HSiCl2X (X = Me and Cl) to the alkene (CF3)2NOCH2CH=CH2 gives the adducts (CF3)2NOCH2CH2CH2SiCl2X (29, X = Me) and (28, X = Cl)in high yield.The substituted dichlorosilanes (CF3)2NOCH2CH2SiEtCl2 (9), (CF3)2NOCHMeCH2SiMeCl2 (14) and (CF3)2NOCH2CH2CH2SiMeCl2 (29) are converted into corresponding polysiloxanes ("prepolymers" of low molecular weight) by reaction with reagents including water, acid, base and metal oxides; equilibration of the polysiloxane "prepolymer" 38, derived from dichlorosilane 29 by heating with powdered KOH, affords a solid rubbery polysiloxane.
- Ducker, Graham E.,Tipping, Anthony E.
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p. 253 - 262
(2007/10/02)
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- Chemical and photochemical approaches to amino(aryl) silylenes
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Generation by two different methods of silylenes stabilized by o-amino(aryl) groups is reported.The halodemetallation of difluoro- or dichloro-silanes with Li metal or lithium-naphthalene gave the same product, a stabilized sila-ylide (hypercoordinated silylene).Intramolecular Lewis base stabilization is not sufficient to isolate a monomeric species.The silylenes, however, have been trapped with 2,3-dimethylbutadiene.An unexpected intramolecular rearrangement to silaacenaphthene has been observed in the case of a six-membered ring amino(aryl) coordinated silylene.Photolysis of o-1--2-benzene produced, among other products, Me3SiSiMe3 and the sila-ylide, which has been trapped with Et3SiH and dimethylbutadiene.Our mechanistic interpretation is supported by spectral observation of the photochemically generated reaction intermediates in a 3-methylpentane glass at low temperature. Key words: Silylene; Sila-ylide; Amino-aryl; Alkali metals; Stabilization; Photochemistry
- Corriu, Robert,Lanneau, Gerard,Priou, Christian,Soulairol, Florence,Auner, Norbert,et al.
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- Pulse Technique Pyrolysis of some Arylsilanes and Their Thermal Reactions with Aliphatic and Aromatic Alcohols Over Ni-Y-Zeolite
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p-Tolyltrimethylsilane and phenyltrimethylsilane were subjected in the gas phase to pyrolysis and thermolysis reactions with alcohols and phenols at different temperatures over Ni Y-zeolite using a pulse catalytic technique.The obtained alkoxy- and phenoxy-trimethylsilanes with other side products were identified by gas liquid chromatographic analysis.The yield in each case varied with the reaction temperature.The highest yield was obtained at 250 deg C.The different pathways of these thermolysis reactions are discussed and the results are assigned.
- Ramadan, N. A.,Abo-Elenin, O. M.,Badawi, A. M.
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- A handy preparation of bis(trimethylsilyl)methylamine
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Reductive silylation of trimethylsilylcyanide provides a new and easy route to bis(trimethylsilyl)-methylamine, a versatile synthon.
- Picard, Jean-Paul,Grelier, Stephane,Dunogues, Jacques,Aizpurua, Jesus-Maria,Palomo, Claudio
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- υ-Ray- and UV-induced Generation of Methyl(phenyl)silylene and Silene Species from Heptamethyl-2-phenyltrisilane
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A benzene solution of heptamethyl-2-phenyltrisilane (1) has been irradiated with γ-rays in the presence of methanol.Hexamethyldisilane, methoxymethyl(phenyl)silane (2) and a 1-methoxytetramethyldisilanyl- and trimethylsilyl-substituted cyclohexadiene (3) were produced.The formation of 2 and 3 can be interpreted in terms of reactions of methanol with methyl(phenyl)silylene and a silicon-carbon double-bonded intermediate (silene), respectively.These intermediates are generated as follows.Benzene is first excited by γ-rays and by collisions the energy transfers to 1.Excited 1 decomposes to give methyl(phenyl)silylene or undergoes rearrangement to a silene intermediate as when 1 is excited by UV light.A kinetic study revealed that the energy transfer in the γ-irradiated system is the same as that in a UV-irradiated system.
- Nakao, Ren,Oka, Kunio,Irie, Setsuko,Dohmaru, Takaaki,Abe, Yasuo,et al.
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p. 755 - 757
(2007/10/02)
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- Photochemical reactions of aryl-substituted catenates of group 4B elements, PhMe2E-E'Me3 (E, E' = Si and Ge). Formation of a radical pair
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Photochemical reactions of phenyl substituted catenates of group 4B elements, PhMe2E-E'Me3 (E, E' = Si and Ge) have been investigated by chemical trapping experiments and laser flash-photolysis.On irradiation, the phenylated group 4B catenate undergoes E-E' bond homolysis to give a pair of radicals (PhMe2E. and Me3E'.).In CCl4, these radicals are converted to the corresponding chlorides by abstraction of a chlorine atom.In a nonhalogenated solvent, the radical pair couples at the ipso-position of the phenyl group of the pairing radical (PhMe2E.) to yield the cor responding diradical.This undergoes either elimination of a divalent species (Me2E:) with concomitant formation of trimethylphenyl group 4B element PhMe3E') or intramolecular 1,2-group 4B element migration to yield group 4B metal-carbon double bonded species.The radical escapes from the solvent cage coupled to the metal atom of the radical to yield the dimetallic product.The reaction path observed is highly dependent on the nature of the group 4B element comprising the phenyl substituted catenate.
- Mochida, Kunio,Kikkawa, Haruhiko,Nakadaira, Yasuhiro
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- New photochemical routes to germylenes and germenes and kinetic evidence concerning the germylene-diene addition mechanism
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Upon 254-nm irradiation of phenylbis(trimethylsilyl)germanes, there is competition between two germylene-forming reactions, the unexpected elimination of phenyltrimethylsilane and the elimination of hexamethyldisilane. Irradiation of a phenylmonosilylgermane PhGeMe2SiMe3 leads to predominant elimination of PhSiMe3, forming dimethylgermylene Me2Ge:, accompanied by migration of Me3Si to the ortho position of the phenyl ring, forming a germene. Laser flash photolysis of PhGeMe2SiMe3 is a convenient source of Me3Ge:, and rate constants are reported for Me2Ge: addition to a series of dienes and other substrates. The kinetic data are in accord with 1,2-addition as the dominant pathway for addition of Me2Ge: to 1,3-dienes.
- Bobbitt, Kevin L.,Maloney, Vincent M.,Gaspar, Peter P.
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p. 2772 - 2777
(2008/10/08)
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- Electroreductive Formation of Polysilanes
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Electroreduction of dichlorosilanes, such as 1,1-dichlorodialkylsilanes, 1,2-dichlorotetra-alkyldisilanes, and 1,4-bis(chlorodialkylsilyl)benzenes, with Mg electrodes in a single-compartment cell was found to yield the corresponding polysilanes.
- Shono, Tatsuya,Kashimura, Shigenori,Ishifune, Manabu,Nishida, Ryoichi
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p. 1160 - 1161
(2007/10/02)
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- Reaction of phenyl(trimethylsilyl)silylene with chloromethanes; Insertion into C-Cl bond and abstraction of chlorine and HCl
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Photolysis of tris(trimethylsilyl)phenylsilane in chloromethanes, ClnCX(4-n), (n = 1-4, X = H, alkyl, and Cl) produced phenyl(trimethylsilyl)silylene as a major intermediate, which afforded three types of products: 1,1-dichloro-1-phenyltrimethyldisilane via abstraction of two chlorine atoms, 1-alkyl-1-chloro-1-phenyltrimethyl-disilane via insertion into the C-Cl bond, and 1-chloro-1-phenyl-2,2,2-trimethyldisilane via abstraction of HCl.Possible reaction mechanisms for the formation of these products were discussed based on initial formation of an 1,2-zwitterionic intermediate.A small amount of a radical-reaction product, 2-chloro-2-phenyl-hexamethyltrisilane, and a product considered to be a cyclohexadienyl derivative were detected in all cases as minor products.
- Oka, Kunio,Nakao, Ren
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- Electronic absorption spectra of diorganogermylenes in matrices: Formation of diorganogermylene complexes with heteroatom-containing substrates
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Diorganogermylenes were generated in hydrocarbon matrices at 77 K by the photolysis of 7-germanorbornadienes 1a-e or bis(trimethylsilyl)germanes 2a-g. The germylenes show electronic absorption bands at 420-558 nm. The germylenes react with heteroatom-containing substrates (R2O, R2S, R3P, R3N, RCl, and ROH) to form adducts, which show characteristic absorption bands at shorter wavelengths than those of germylenes.
- Ando, Wataru,Itoh, Hiroyuki,Tsumuraya, Takeshi
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p. 2759 - 2766
(2008/10/08)
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- PHOTOSILYLATION OF ELECTRON-DEFICIENT ALKENES BY USE OF DISILANES VIA PHOTOINDUCED ELECTRON-TRANSFER
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The photosilylation on electron-deficient alkenes such as 1-aryl-2,2-dicyanoethenes occurred regioselectively at the β-position to the electron-withdrawing groups upon irradiation with disilanes and trisilane.
- Mizuno, Kazuhiko,Nakanishi, Kazuhisa,Chosa, Jun-ichi,Nguyen, Tien,Otsuji, Yoshio
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p. 3689 - 3692
(2007/10/02)
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- Efficient formation and cleavage of disilanes by potassium-graphite. Silylation with silyl metal reagents
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Potassium-graphite laminate (C8K) very rapidly forms disilanes from chlorosilanes and then rapidly cleaves the disilanes to give silyl potassium reagents which can be converted into potassium silyl cuprates, -manganates, and -vanadates that are useful for various nucleophilic substitution and addition reactions.
- Fuerstner, Alois,Weidmann, Hans
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- Process for the preparation of hexaalkyldisilane
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A process for the preparation of hexaalkyldisilane. A trialkylsilane halide is brought into contact with an alkali metal, a salt and a phase transfer agent.
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- A Facile Synthesis of Tetrakis(trimethylsilyl)butatriene Properties and Cycloadditions
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Tetrakis(trimethylsilyl)butatriene was readily prepared by flash vacuum pyrolysis of hexakis(trimethylsilyl)-2-butyne.The physical and chemical properties of the butatriene are described.
- Sakurai, Hideki,Kudo, Muneo,Sakamoto, Kenkichi,Nakadaira, Yasuhiro,Kira, Mitsuo,Sekiguchi, Akira
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p. 1441 - 1444
(2007/10/02)
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- Low-temperature photochemistry of (η5-C5 Me5)Fe(CO)2CH2SiMe2H: Establishment of (η5-C5Me5)Fe(CO)(CH2SiMe 2)H as the intermediate in the rearrangement of (η5-C5Me5)Fe(CO)2CH ...
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Full title: Low-temperature photochemistry of (η5-C5 Me5)Fe(CO)2CH2SiMe2H: Establishment of (η5-C5Me5)Fe(CO)(CH2SiMe 2)H as the intermediate in the rearrangement of (η5-C5Me5)Fe(CO)2CH 2SiMe2H to (η5-C5Me5)Fe(CO)2SiMe 3. Near-UV (355-nm) photolysis of (η5-C5Me5)Fe(CO)2CH 2SiMe2H in alkane solution under 1 atm of CO or saturated with PPh3 results in the nearly quantitative formation of (η5-C5Me5)Fe(CO)(L)SiMe3 (L = CO, PPh3). The intermediate in this rearrangement is shown to be (η5-C5Me5)Fe(CO)(CH2SiMe 2)H by low-temperature IR, UV-vis, and NMR studies. Near-UV irradiation of (η5-C5Me5)Fe(CO)2CH 2SiMe2H at 77 K in a 1-pentene or 2-methyltetrahydrofuran matrix results in loss of CO as evidenced by the growth of an IR absorption due to, free CO at 2132 cm-1. A 16e (η5-C5Me5)Fe(CO)CH2SiMe 2H cannot be trapped by the donor matrices, nor can it be detected under any conditions used. Rather, even at 77 K the β-H is transferred from the Si to the Fe as evidenced by the decline of the IR absorption at 2101 cm-1 associated with the Si-H bond. Although β-H transfer is the major photoprocess in alkane matrices at 77 K, the direct rearrangement of approximately 20% of the (η5-C5Me5)Fe(CO)2CH 2SiMe2H to (η5-C5Me5)Fe(CO)2SiMe 3 is evidence for radical formation as a minor primary photoprocess. The (η5-C5Me5)Fe(CO) (CH2SiMe2)H resulting from β-H transfer is inert up to 225 K. The 1H NMR of (η5-C5Me5)Fe(CO)(CH2SiMe 2)H indicates that the complex is not fluxional even at the highest temperature at which it is chemically inert. This finding is consistent with the formulation of the M(CH2SiMe2) unit as a metallasilacyclopropane. Irradiation of (η5-C5Me5)Fe(CO)2CH 2SiMe2H in a 1 M PEt3 alkane solution at 200 K results only in the formation of (η5-C5Me5)Fe(CO)(CH2SiMe 2)H. Warming of (η5-C5Me5)Fe(CO)(CH2SiMe 2)H to 225 K in the presence of 1 atm of CO or PEt3 results in the formation of (η5-C5Me5)Fe(CO)(L)SiMe3 (L = CO, PEt3). The results confirm that M(CH2SiMe2)(H) complexes are intermediates in the conversion of M-CH2SiMe2H complexes to M-SiMe3 complexes.
- Randolph, Claudia Lewis,Wrighton, Mark S.
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p. 365 - 371
(2008/10/08)
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