617-86-7Relevant articles and documents
Incorporation of trialkylsilyl and trialkylstannyl groups into ruthenium carbonyl clusters. Carbonyl substitution versus trialkylsilane or trialkylstannane elimination in these clusters
Cabeza, Javier A.,Llamazares, Angela,Riera, Víctor,Triki, Smail,Ouahab, Lahcène
, p. 3334 - 3339 (1992)
The clusters [Ru3(μ-H)(μ3,η2-ampy)(PPh 3)n(CO)9-n] (n = 0 (1), 1 (2), 2 (3); Hampy = 2-amino-6-methylpyridine) react with HSiEt3 to give the oxidative substitution products [Ru3(μ-H)2(μ3,η 2-ampy)-(SiEt3)(PPh3)n(CO) 8-n] (n = 0 (4a), 1 (5a), 2 (6a)). Similar reactions of 1-3 with HSnBu3 afford [Ru3(μ-H)2(μ3,η 2-ampy)(SnBu3)(PPh3)n(CO) 8-n] (n = 0 (4b), 1 (5b), 2 (6b)). In all cases, (a) the added hydride spans a metal-metal edge adjacent to that supported by the bridging amido group, (b) the SiEt3 or SnBu3 ligands occupy an equatorial site on the Ru atom bound to the two hydrides, being trans to the hydride which spans the same edge as the amido group, and (c) in the compounds containing PPh3 ligands, these ligands occupy equatorial positions, cis to hydrides, on the Ru atoms bound to only one hydride. The reactions of 4a and 5a with PPh3 produce the elimination of HSiEt3, rendering the complexes 2 and 3, respectively; however, similar reactions of the tin-containing compounds 4b and 5b afford the substitution products 5b and 6b, respectively. The compounds have been characterized by infrared and 1H, 13C, and 31P NMR spectroscopies and, in the case of 4a by X-ray diffraction. Crystal data for 4a: monoclinic, space group P21/n, a = 10.849 (8) A?, b = 20.809 (4) A?, c = 12.049 (8) A?, β = 98.21 (5)°, V = 2692 (2) A?3, Z = 4, μ(Mo Kα) = 17.17 cm-1, R = 0.048, Rw = 0.053 for 2036 reflections and 287 variables.
First observation of stable primary radical cations tBu3SiH cation radical formed by directed radiolysis of a pure compound: tBu3SiH
Rhodes, Christopher J.
, p. 19 - 23 (1993)
Following γ-irradiation of neat t-Bu3SiH at 77 K, the ESR spectrum of the primary radical cation was observed; in contrast Et3SiH yields only radicals arising from secondary processes.
ArF laser photolysis of tetraethyl- and tetravinyl silane
Pola, Josef,Parsons, Jonathan P.,Taylor, Roger
, p. C9 - C11 (1995)
The ArF laser-induced photolysis of tetraethyl- and tetravinyl-silane (C2Hn)4Si, (n=3 and 5), affords C2Hn-1 unsaturates and a silicon-containing deposit.The reactions are suitable for use in low-temperature chemical vapour deposition of Si/C materials.Keywords: Silicon; Silicon carbide; Laser photolysis; Tetraethylsilane; Tetravinylsilane
Unlocking the Catalytic Hydrogenolysis of Chlorosilanes into Hydrosilanes with Superbases
Durin, Gabriel,Berthet, Jean-Claude,Nicolas, Emmanuel,Cantat, Thibault
, p. 10855 - 10861 (2021/09/08)
The efficient synthesis of hydrosilanes by catalytic hydrogenolysis of chlorosilanes is described using an iridium (III) pincer catalyst. A careful selection of a nitrogen base (including sterically hindered guanidines and phosphazenes) can unlock the preparation of Me3SiH, Et3SiH, and Me2SiHCl in high yield (up to 98%) directly from their corresponding chlorosilanes.
Regioselective Hydrosilylation of Olefins Catalyzed by a Molecular Calcium Hydride Cation
Schuhknecht, Danny,Spaniol, Thomas P.,Maron, Laurent,Okuda, Jun
supporting information, p. 310 - 314 (2019/11/26)
Chemo- and regioselectivity are often difficult to control during olefin hydrosilylation catalyzed by d- and f-block metal complexes. The cationic hydride of calcium [CaH]+ stabilized by an NNNN macrocycle was found to catalyze the regioselective hydrosilylation of aliphatic olefins to give anti-Markovnikov products, while aryl-substituted olefins were hydrosilyated with Markovnikov regioselectivity. Ethylene was efficiently hydrosilylated by primary and secondary hydrosilanes to give di- and monoethylated silanes. Aliphatic hydrosilanes were preferred over other commonly employed hydrosilanes: Arylsilanes such as PhSiH3 underwent scrambling reactions promoted by the nucleophilic hydride, while alkoxy- and siloxy-substituted hydrosilanes gave isolable alkoxy and siloxy calcium derivatives.
Dual Role of Doubly Reduced Arylboranes as Dihydrogen- and Hydride-Transfer Catalysts
Von Grotthuss, Esther,Prey, Sven E.,Bolte, Michael,Lerner, Hans-Wolfram,Wagner, Matthias
supporting information, (2019/04/17)
Doubly reduced 9,10-dihydro-9,10-diboraanthracenes (DBAs) are introduced as catalysts for hydrogenation as well as hydride-transfer reactions. The required alkali metal salts M2[DBA] are readily accessible from the respective neutral DBAs and Li metal, Na metal, or KC8. In the first step, the ambiphilic M2[DBA] activate H2 in a concerted, metal-like fashion. The rates of H2 activation strongly depend on the B-bonded substituents and the counter cations. Smaller substituents (e.g., H, Me) are superior to bulkier groups (e.g., Et, pTol), and a Mes substituent is even prohibitively large. Li+ ions, which form persistent contact ion pairs with [DBA]2-, slow the H2-addition rate to a higher extent than more weakly coordinating Na+/K+ ions. For the hydrogenation of unsaturated compounds, we identified Li2[4] (Me substituents at boron) as the best performing catalyst; its substrate scope encompasses Ph(H)CNtBu, Ph2CCH2, and anthracene. The conversion of E-Cl to E-H bonds (E = C, Si, Ge, P) was best achieved by using Na2[4]. The latter protocol provides facile access also to Me2Si(H)Cl, a most important silicone building block. Whereas the H2-transfer reaction regenerates the dianion [4]2- and is thus immediately catalytic, the H--transfer process releases the neutral 4, which has to be recharged by Na metal before it can enter the cycle again. To avoid Wurtz-type coupling of the substrate, the reduction of 4 must be performed in the absence of the element halide, which demands an alternating process management (similar to the industrial anthraquinone process).
Dual Role of Doubly Reduced Arylboranes as Dihydrogen- and Hydride-Transfer Catalysts
Von Grotthuss, Esther,Prey, Sven E.,Bolte, Michael,Lerner, Hans-Wolfram,Wagner, Matthias
supporting information, p. 6082 - 6091 (2019/04/17)
Doubly reduced 9,10-dihydro-9,10-diboraanthracenes (DBAs) are introduced as catalysts for hydrogenation as well as hydride-transfer reactions. The required alkali metal salts M2[DBA] are readily accessible from the respective neutral DBAs and Li metal, Na metal, or KC8. In the first step, the ambiphilic M2[DBA] activate H2 in a concerted, metal-like fashion. The rates of H2 activation strongly depend on the B-bonded substituents and the counter cations. Smaller substituents (e.g., H, Me) are superior to bulkier groups (e.g., Et, pTol), and a Mes substituent is even prohibitively large. Li+ ions, which form persistent contact ion pairs with [DBA]2-, slow the H2-addition rate to a higher extent than more weakly coordinating Na+/K+ ions. For the hydrogenation of unsaturated compounds, we identified Li2[4] (Me substituents at boron) as the best performing catalyst; its substrate scope encompasses Ph(H)C=NtBu, Ph2C=CH2, and anthracene. The conversion of E-Cl to E-H bonds (E = C, Si, Ge, P) was best achieved by using Na2[4]. The latter protocol provides facile access also to Me2Si(H)Cl, a most important silicone building block. Whereas the H2-transfer reaction regenerates the dianion [4]2- and is thus immediately catalytic, the H--transfer process releases the neutral 4, which has to be recharged by Na metal before it can enter the cycle again. To avoid Wurtz-type coupling of the substrate, the reduction of 4 must be performed in the absence of the element halide, which demands an alternating process management (similar to the industrial anthraquinone process).
Interconversion and reactivity of manganese silyl, silylene, and silene complexes
Price, Jeffrey S.,Emslie, David J. H.
, p. 10853 - 10869 (2019/12/23)
Manganese disilyl hydride complexes [(dmpe)2MnH(SiH2R)2] (4Ph: R = Ph, 4Bu: R = nBu) reacted with ethylene to form silene hydride complexes [(dmpe)2MnH(RHSiCHMe)] (6Ph,H: R = Ph, 6Bu,H: R = nBu). Compounds 6R,H reacted with a second equivalent of ethylene to generate [(dmpe)2MnH(REtSiCHMe)] (6Ph,Et: R = Ph, 6Bu,Et: R = nBu), resulting from apparent ethylene insertion into the silene Si-H bond. Furthermore, in the absence of ethylene, silene complex 6Bu,H slowly isomerized to the silylene hydride complex [(dmpe)2MnH(SiEtnBu)] (3Bu,Et). Reactions of 4R with ethylene likely proceed via low-coordinate silyl {[(dmpe)2Mn(SiH2R)] (2Ph: R = Ph, 2Bu: R = nBu)} or silylene hydride {[(dmpe)2MnH(SiHR)] (3Ph,H: R = Ph, 3Bu,H: R = nBu)} intermediates accessed from 4R by H3SiR elimination. DFT calculations and high temperature NMR spectra support the accessibility of these intermediates, and reactions of 4R with isonitriles or N-heterocyclic carbenes yielded the silyl isonitrile complexes [(dmpe)2Mn(SiH2R)(CNR′)] (7a-d: R = Ph or nBu; R′ = o-xylyl or tBu), and NHC-stabilized silylene hydride complexes [(dmpe)2MnH{SiHR(NHC)}] (8a-d: R = Ph or nBu; NHC = 1,3-diisopropylimidazolin-2-ylidene or 1,3,4,5-Tetramethyl-4-imidazolin-2-ylidene), respectively, all of which were crystallographically characterized. Silyl, silylene and silene complexes in this work were accessed via reactions of [(dmpe)2MnH(C2H4)] (1) with hydrosilanes, in some cases followed by ethylene. Therefore, ethylene (C2H4 and C2D4) hydrosilylation was investigated using [(dmpe)2MnH(C2H4)] (1) as a pre-catalyst, resulting in stepwise conversion of primary to secondary to tertiary hydrosilanes. Various catalytically active manganese-containing species were observed during catalysis, including silylene and silene complexes, and a catalytic cycle is proposed.
Synthesis of hydrosilanes: Via Lewis-base-catalysed reduction of alkoxy silanes with NaBH4
Aoyagi, Keiya,Ohmori, Yu,Inomata, Koya,Matsumoto, Kazuhiro,Shimada, Shigeru,Sato, Kazuhiko,Nakajima, Yumiko
supporting information, p. 5859 - 5862 (2019/05/27)
Hydrosilanes were synthesized by reduction of alkoxy silanes with BH3 in the presence of hexamethylphosphoric triamide (HMPA) as a Lewis-base catalyst. The reaction was also achieved using an inexpensive and easily handled hydride source NaBH4, which reacted with EtBr as a sacrificial reagent to form BH3in situ.
Catalytic Reduction of Alkoxysilanes with Borane Using a Metallocene-Type Yttrium Complex
Aoyagi, Keiya,Matsumoto, Kazuhiro,Shimada, Shigeru,Sato, Kazuhiko,Nakajima, Yumiko
supporting information, p. 210 - 212 (2019/02/01)
The catalytic reduction of alkoxysilanes with the borane HBpin (pin = pinacolato) was achieved using a metallocene-type yttrium complex as a catalyst precursor. Mechanistic study supported the pivotal role of the rigid metallocene structure of the catalyst, which bears two bulky n5-C5Me4SiMe3 ligands, in suppressing the coordination of the side product MeOBpin that is generated during the reaction.
