631-36-7Relevant academic research and scientific papers
Heterogeneous Rates of Electron Transfer. Application of Cyclic Voltammetric Techniques to Irreversible Electrochemical Processes
Klingler, R. J.,Kochi, J. K.
, p. 4790 - 4798 (1980)
The anodic peak potentials in the irreversible cyclic voltammograms of various homoleptic alkylmetals in acetonitrile show a striking linear correlation with their ionization potentials ID determined in the gas phase.Application of various transient electrochemical techniques proves that the electrode process arises from a totally irreversible ECE sequence in which the peak potential is determined solely by the kinetics of heterogeneous electron transfer and diffusion-uncomplicated by any follow-up chemical reaction.As a result, the anodic peak potential Ep can be directly related to the activation free energy for electron transfer, and the correlation of EP and ID represents a linear free-energy relationship.The mechanism of heterogeneous electron transfer is described as an outer-sphere process, dependent only on the driving force for one-electron oxidation and independent of steric effects of the alkylmetal.The close relationship between the activated compexes for heterogeneous and homogeneous electron transfer is emphasized in a direct comparison of the electrochemical process with the oxidation of the same alkylmetals by a series of poly(pyridine)iron(III) complexes in solution.
Ruthenium-Catalyzed Coupling Reactions of CO2 with C2H4 and Hydrosilanes towards Silyl Esters
Kunihiro, Kana,Heyte, Svetlana,Paul, Sébastien,Roisnel, Thierry,Carpentier, Jean-Fran?ois,Kirillov, Evgueni
supporting information, p. 3997 - 4003 (2021/02/01)
A series of in situ-prepared catalytic systems incorporating RuII precursors and bidentate phosphine ligands has been probed in the reductive carboxylation of ethylene in the presence of triethylsilane as reductant. The catalytic production of propionate and acrylate silyl esters was evidenced by high-throughput screening (HTS) and implemented in batch reactor techniques. The most promising catalyst systems identified were made of Ru(H)(Cl)(CO)(PPh3)3 and 1,4-bis(dicyclohexylphosphino)butane (DCPB) or 1,1’-ferrocene-diyl-bis(cyclohexylphosphine) (DCPF). A marked influence of water on the acrylate/propionate selectivity was noted. Turnover numbers [mol mol(Ru)?1] up to 16 for acrylate and up to 68 for propionate were reached under relatively mild conditions (20 bar, 100 °C, 0.5 mol % Ru, 40 mol % H2O vs. HSiEt3). Possible mechanisms are discussed.
Towards Naked Zinc(II) in the Condensed Phase: A Highly Lewis Acidic ZnII Dication Stabilized by Weakly Coordinating Carborate Anions
Adet, Nicolas,Specklin, David,Gourlaouen, Christophe,Damiens, Thibault,Jacques, Béatrice,Wehmschulte, Rudolf J.,Dagorne, Samuel
supporting information, p. 2084 - 2088 (2020/11/30)
The employment of the hexyl-substituted anion [HexCB11Cl11]? allowed the synthesis of a ZnII species, Zn[HexCB11Cl11]2, 3, in which the Zn2+ cation is only weakly coordinated to two carborate counterions and that is soluble in low polarity organic solvents such as bromobenzene. DOSY NMR studies show the facile displacement of at least one of the counterions, and this near nakedness of the cation results in high catalytic activity in the hydrosilylation of 1-hexene and 1-methyl-1cyclohexene. Fluoride ion affinity (FIA) calculations reveal a solution Lewis acidity of 3 (FIA=262.1 kJ mol?1) that is higher than that of the landmark Lewis acid B(C6F5)3 (FIA=220.5 kJ mol?1). This high Lewis acidity leads to a high activity in catalytic CO2 and Ph2CO reduction by Et3SiH and hydrogenation of 1,1-diphenylethylene using 1,4-cyclohexadiene as the hydrogen source. Compound 3 was characterized by multinuclear NMR spectroscopy, mass spectrometry, single crystal X-ray diffraction, and DFT studies.
Additive-free Semihydrogenation of an Alkynyl Group to an Alkenyl Group over Pd?TiO2 Photocatalyst Utilizing Temporary In-situ Deactivation
Kojima, Yasumi,Fukui, Makoto,Tanaka, Atsuhiro,Hashimoto, Keiji,Kominami, Hiroshi
, p. 3605 - 3611 (2018/08/01)
Lindlar's catalyst, i. e., calcium carbonate-supported palladium (Pd) modified with lead, has been used for semihydrogenation of an alkynyl group in the presence of hydrogen gas (H2). We examined hydrogenation of an alkynyl group in organosilane and hydrocarbon in methanolic suspensions of a Pd-loaded titanium(IV) oxide (Pd?TiO2) photocatalyst without the use of additives and H2. In the photocatalytic reaction, Pd particles worked as co-catalysts for hydrogenation and alkyne hydrogenation had priority to alkene hydrogenation. Since the Pd co-catalyst was temporarily deactivated during the reaction owing to accumulation of the oxidized product(s) of methanol, the capacity of hydrogenation of the unsaturated C?C bond was limited. By optimizing the capacity and amount of alkynes, almost complete semihydrogenation of alkynes was achieved under a poison-free condition. Pd?TiO2 can be regenerated by very simple treatments, i. e., washing and drying at room temperature.
MONONUCLEAR IRON COMPLEX AND ORGANIC SYNTHESIS REACTION USING SAME
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Paragraph 0218-0220, (2016/12/01)
Provided is a mononuclear iron complex that comprises an iron-silicon bond that is represented by formula (1) and that exhibits excellent catalyst activity in each of a hydrosilylation reaction, a hydrogenation reaction, and reduction of a carbonyl compound. In formula (1), R 1 -R 6 either independently represent an alkyl group, an aryl group, an aralkyl group or the like that may be substituted with a hydrogen atom or X, or represent a crosslinking substituent in which at least one pair comprising one of R 1 -R 3 and one of R 4 -R 6 is combined. X represents a halogen atom, an organoxy group, or the like. L represents a two-electron ligand other than CO. When a plurality of L are present, the plurality of L may be the same as or different from each other. When two L are present, the two L may be bonded to each other. n and m independently represent an integer of 1 to 3 with the stipulation that n+m equals 3 or 4.
Catalytic study of heterobimetallic rhodium complexes derived from partially alkylated s-indacene in dehydrogenative silylation of olefins
Adams,Riviere,Riviere-Baudet,Morales-Verdejo,Dahrouch,Morales,Castel,Delpech,Manríquez,Chávez
, p. 266 - 274 (2013/11/19)
This work describes the catalytic study of heterobimetallic rhodium compounds derived from partially alkylated s-indacene in dehydrogenative silylation of olefins in order to elucidate as much as possible the effects of: solvent, temperature, chemical substrates, olefin effect, silane effect, and secondary metallic fragment. The rhodium complexes, anti-[Cp*Fe-s- Ic′-Rh(COD)] 1, anti-[Cp*Ru-s-Ic′-Rh(COD)] 2, and syn-[Cp*Ru-s-Ic′-Rh(COD)] 2′ (with s-Ic′: 2,6-diethyl-4,8-dimethyl-s-indaceneiide) were previously synthesized and characterized, and were compared with the catalytic activity of the complexes previously reported; monometallic [(COD)Rh-s-Ic′H] 3, and homobimetallic anti-[{(COD)Rh}2-s-Ic′] 4, and syn-[{(COD)Rh} 2-s-Ic′] 4′. The heterobimetallic complexes show a high activity and selectivity for the dehydrogenative silylation of styrene and these complexes show also the presence of a cooperative effect between both metallic centers, which is evidenced when compared with monometallic complex.
Synthesis of the first persilylated ammonium ion, [(Me3Si) 3NSi(H)Me2]+, by silylium-catalyzed methyl/hydrogen exchange reactions
Labbow, Rene,Reiss, Fabian,Schulz, Axel,Villinger, Alexander
supporting information, p. 3223 - 3226 (2014/08/05)
This work describes the unexpected synthesis and characterization of the first persilylated ammonium ion, [(Me3Si)3NSi(H)Me 2]+, in the reaction of (Me3Si)3N with [Me3Si-H-SiMe3][B(C6F5) 4]. NMR and Raman studies revealed a transition-metal-free silylium ion catalyzed substituent redistribution process when [Me3Si-H- SiMe3]+ was used as the silylating reagent. These observations were affirmed in the reaction with [Et3Si-H-SiEt 3][B(C6F5)4]. A Lewis acid catalyzed scrambling process always occurs if an excess of silanes is present in the formation of silylium cations while employing the standard Bartlett-Schneider- Condon type reaction. Additionally, the thermodynamics of this process was accessed by DFT computations at the pbe1pbe/aug-cc-pVDZ level, indicating alkyl substituent exchange equilibria at the silane and preference of the formation of [(Me3Si)3NSi(H)Me2]+ over [(Me 3Si)4N]+.
Catalyst design for iron-promoted reductions: An iron disilyl-dicarbonyl complex bearing weakly coordinating η2-(H-Si) moieties
Sunada, Yusuke,Tsutsumi, Hironori,Shigeta, Keisuke,Yoshida, Ryota,Hashimoto, Toru,Nagashima, Hideo
supporting information, p. 16687 - 16692 (2013/12/04)
Iron disilyl dicarbonyl complex 1, in which two H-Si moieties of the 1,2-bis(dimethylsilyl)benzene ligand were coordinated to the iron center in an η2-(H-Si) fashion, was synthesized by the reaction of (η4-C6H8)Fe(CO)3 with 2 equiv. of 1,2-bis(dimethylsilyl)benzene under photo-irradiation. Complex 1 demonstrated high catalytic activity toward the hydrogenation of alkenes, the hydrosilylation of alkenes and the reduction of carbonyl compounds.
Deoxygenative reduction of carbon dioxide to methane, toluene, and diphenylmethane with [Et2Al]+ as catalyst
Khandelwal, Manish,Wehmschulte, Rudolf J.
supporting information; experimental part, p. 7323 - 7326 (2012/09/08)
The strong Lewis acid [Et2Al]+ catalyzes the reduction of carbon dioxide with hydrosilanes under mild conditions to methane. In benzene solution, the side products toluene and diphenylmethane are also obtained through Lewis acid catalyzed benzene alkylation by reaction intermediates. Copyright
Probing the catalytic potential of chloro nitrosyl rhenium(i) complexes
Jiang, Yanfeng,Blacque, Olivier,Berke, Heinz
experimental part, p. 2578 - 2587 (2011/05/03)
The reduction of the mononitrosyl Re(ii) salt [NMe4] 2[ReCl5(NO)] (1) with zinc in acetonitrile afforded the Re(i) dichloride complex [ReCl2(NO)(CH3CN)3] (2). Subsequent ligand substitution reactions with PCy3, PiPr 3 and P(p-tolyl)3 afforded the bisphosphine Re(i) complexes [ReCl2(NO)(PR3)2(CH3CN)] (3, R = Cy a, iPr b, p-tolyl c) in good yields. The acetonitrile ligand in 3 is labile, permitting its replacement with H2 (1 bar) to afford the dihydrogen Re(i) complexes [ReCl2(NO)(PR3) 2(η2-H2)] (4, R = Cy a, iPr b). The catalytic activity of 2, 3 and 4 in hydrogen-related catalyses including dehydrocoupling of Me2NH·BH3, dehydrogenative silylation of styrenes, and hydrosilylation of ketones and aryl aldehydes were investigated, with the main focus on phosphine and halide effects. In the dehydrocoupling of Me2NH·BH3, the phosphine-free complex 2 exhibits the same activity as the bisphosphine-substituted systems. In the dehydrogenative silylation of styrenes, 3a and 4a bearing PCy3 ligands exhibit high catalytic activities. Monochloro Re(i) hydrides [Re(Cl)(H)(NO)(PR3)2(CH3CN)] (5, R = Cy a, iPr b) were proven to be formed in the initiation pathway. The phosphine-free complex 2 showed in dehydrogenative silylations even higher activity than the bisphosphine derivatives, which further emphasizes the importance of a facile phosphine dissociation in the catalytic process. In the hydrosilylation of ketones and aryl aldehydes, at least one rhenium-bound phosphine is required to ensure high catalytic activity.
