279-23-2Relevant articles and documents
Traynham
, p. 833,834 (1960)
Norbornane: An investigation into its valence electronic structure using electron momentum spectroscopy, and density functional and Green's function theories
Knippenberg,Nixon,Brunger,Maddern,Campbell,Trout,Wang,Newell,Deleuze,Francois,Winkler
, p. 10525 - 10541 (2004)
We report on the results of an exhaustive study of the valence electronic structure of norbornane (C7H12), up to binding energies of 29 eV. Experimental electron momentum spectroscopy and theoretical Green's function and density functional theory approaches were all utilized in this investigation. A stringent comparison between the electron momentum spectroscopy and theoretical orbital momentum distributions found that, among all the tested models, the combination of the Becke-Perdew functional and a polarized valence basis set of triple-ζ quality provides the best representation of the electron momentum distributions for all of the 20 valence orbitals of norbornane. This experimentally validated quantum chemistry model was then used to extract some chemically important properties of norbornane. When these calculated properties are compared to corresponding results from other independent measurements, generally good agreement is found. Green's function calculations with the aid of the third-order algebraic diagrammatic construction scheme indicate that the orbital picture of ionization breaks down at binding energies larger than 22.5 eV. Despite this complication, they enable insights within 0.2 eV accuracy into the available ultraviolet photoemission and newly presented (e,2e) ionization spectra, except for the band associated with the 1a2-1 one-hole state, which is probably subject to rather significant vibronic coupling effects, and a band at ~25 eV characterized by a momentum distribution of "s-type" symmetry, which Green's function calculations fail to reproduce. We note the vicinity of the vertical double ionization threshold at ~26 eV.
Boryl-metal bonds facilitate cobalt/nickel-catalyzed olefin hydrogenation
Lin, Tzu-Pin,Peters, Jonas C.
, p. 13672 - 13683 (2014)
New approaches toward the generation of late first-row metal catalysts that efficiently facilitate two-electron reductive transformations (e.g., hydrogenation) more typical of noble-metal catalysts is an important goal. Herein we describe the synthesis of a structurally unusual S = 1 bimetallic Co complex, [(CyPBP)CoH]2(1), supported by bis(phosphino)boryl and bis(phosphino)hydridoborane ligands. This complex reacts reversibly with a second equivalent of H2(1 atm) and serves as an olefin hydrogenation catalyst under mild conditions (room temperature, 1 atm H2). A bimetallic Co species is invoked in the rate-determining step of the catalysis according to kinetic studies. A structurally related NiINiIdimer, [(PhPBP)Ni]2(3), has also been prepared. Like Co catalyst 1, Ni complex 3 displays reversible reactivity toward H2, affording the bimetallic complex [(PhPBHP)NiH]2(4). This reversible behavior is unprecedented for NiIspecies and is attributed to the presence of a boryl-Ni bond. Lastly, a series of monomeric (tBuPBP)NiX complexes (X = Cl (5), OTf (6), H (7), OC(H)O (8)) have been prepared. The complex (tBuPBP)NiH (7) shows enhanced catalytic olefin hydrogenation activity when directly compared with its isoelectronic/isostructural analogues where the boryl unit is substituted by a phenyl or amine donor, a phenomenon that we posit is related to the strong trans influence exerted by the boryl ligand.
Hydrogenation via photochemically generated diimide
Squillacote,De Felippis,Lai
, p. 4137 - 4140 (1993)
Diimide is a well-known reagent for hydrogenating multiple bonds with very high stereospecificity. However, all of the methods for generating diimide require somewhat rigorous conditions. We show here that 1-thia-3,4-diazolidine-2,5-dione (TDADH) can be used to photochemically produce diimide at room temperature under neutral conditions. The diimide thus produced can hydrogenate multiple bonds in high yields.
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Bower, B. K.,Tennent, H. G.
, p. 2512 - 2514 (1972)
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Moore et al.
, p. 2019 (1961)
Comparison of alkene hydrogenation in carbon nanoreactors of different diameters: Probing the effects of nanoscale confinement on ruthenium nanoparticle catalysis
Aygün, Mehtap,Stoppiello, Craig T.,Lebedeva, Maria A.,Smith, Emily F.,Gimenez-Lopez, Maria Del Carmen,Khlobystov, Andrei N.,Chamberlain, Thomas W.
, p. 21467 - 21477 (2017)
The catalytic properties of ruthenium nanoparticles (RuNPs) supported in carbon nanoreactors of different diameters-single walled carbon nanotubes (SWNTs, width of cavity 1.5 nm) and hollow graphitised nanofibers (GNFs, width of cavity 50-70 nm)-were evaluated using exploratory alkene hydrogenation reactions and compared to RuNPs adsorbed on the surface of SWNT or deposited on carbon black in commercially available Ru/C. Supercritical CO2 is shown to be essential to enable efficient transport of reactants to the catalytic RuNPs, particularly for the very narrow RuNP@SWNT nanoreactors. Though the RuNPs in SWNT are observed to be highly active, they simultaneously reduce the accessible volume of very narrow SWNTs by 30-40% resulting in lower overall turnover numbers (TONs). In contrast, RuNPs confined in wider GNFs were completely accessible and demonstrated remarkable activity compared to unconfined RuNPs on the outer surface of SWNTs or carbon black. Control of the nanoscale environment around the catalytic RuNPs significantly enhances the stability of the catalyst and influences the local concentration of reactant molecules in close proximity to the RuNPs, illustrating the comparable importance of confinement to that of metal loading and size of NPs in the catalyst. Interestingly, extreme spatial confinement also appeared not to be the best strategy for controlling the selectivity of hydrogenations in a competitive reaction of norbornene and benzonorbornadiene, with wider RuNP@GNF nanoreactors displaying enhanced selectivity for the hydrogenation of the aromatic group containing alkene (benzonorbornadiene). This is attributed to the presence of nanoscale graphitic step-edges within the GNF making them an attractive alternative to the extremely narrow SWNT nanoreactors for preparative catalysis.
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Wiberg,K.B. et al.
, p. 2711 - 2714 (1976)
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Pd/C-Catalyzed H2 Evolution from Tetrahydroxydiboron Hydrolysis
Zhou, Junjie,Huang, Yu,Shen, Jialu,Liu, Xiang
, p. 3004 - 3010 (2021/02/12)
The production of H2 from non-fossil sources is a key research challenge to contributing solving the forthcoming energy problem. Aqueous solutions of tetrahydroxydiboron have very recently appeared as a H2 source, from which both hydrogen atoms are provided by water, in the presence of highly sophisticated nanocatalysts. Herein, commercial and cheap Pd/C is shown to be an efficient and recyclable catalyst for H2 evolution upon tetrahydroxydiboron hydrolysis. Graphic Abstract: [Figure not available: see fulltext.]
Acid- and Base-Catalyzed Hydrolytic Hydrogen Evolution from Diboronic Acid
Wang, Yi,Shen, Jialu,Huang, Yu,Liu, Xiang,Zhao, Qiuxia,Astruc, Didier
supporting information, p. 3013 - 3018 (2021/03/26)
The efficient production of H2 from hydrogen-rich sources, particularly from water, is a crucial task and a great challenge, both as a sustainable energy source and on the laboratory scale for hydrogenation reactions. Herein, a facile and effective synthesis of H2 and D2 from only acid- or base-catalyzed metal-free hydrolysis of B2(OH)4, a current borylation reagent, has been developed without any transition metal or ligand. Acid-catalyzed H2 evolution was completed in 4 min, whereas the base-catalyzed process needed 6 min. The large kinetic isotopic effects for this reaction with D2O, deuteration experiments and mechanistic studies have confirmed that both H atoms of H2 originate from water using either of these reactions. This new, metal-free catalytic system holds several advantages, such as high efficiency, simplicity of operation, sustainability, economy, and potential further use.
Palladium on carbon as an efficient, durable and economical catalyst for the alcoholysis of B2pin2
Li, Ning,Liu, Xiang,Meng, Xu,Shen, Jialu,Zhou, Junjie
, (2021/06/18)
Hydrogen has attracted much attention as one of the most promising chemical fuel candidates because of its zero emission during consumption. In order to solve the freezing problem of water based hydrolysis process, herein, the Pd/C as an efficient and stable catalyst for the methanolysis, ethanolysis, propanolysis and butanolysis of B2pin2 for the generation of hydrogen has been first developed. The large kinetic isotope effect (KIE) of kH/kD = 5.0, D2 formation from CD3OD and in situ tandem reaction have confirmed that alcohol is the only hydrogen source. Interestingly, the order of Ea of these alcohols in H2 evolution is MeOH (methanol, 29.57 kJ/mol) nBuOH (n-butanol, 41.98 kJ/mol), which is consistent with the known order of acidities of these alcohols (MeOH > EtOH > PrOH > nBuOH).