56 research outputs found

    Bis{1,2-bis­[bis­(3-meth­oxy­prop­yl)phosphan­yl]ethane-κ2 P,P′}dichlorido­osmium(II)

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    In the centrosymmetric title compound, [OsCl2(C18H40O4P2)2], the OsII atom adopts a trans-OsCl2P4 geometry, arising from its coordination by two chelating diphosphane ligands and two chloride ions. One of the meth­oxy side chains of the ligand is disordered over two orientations in a 0.700 (6):0.300 (6) ratio

    Reduction of Borazines Mediated by Low‐Valent Chromium Species

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    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95578/1/13168_ftp.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/95578/2/anie_201206668_sm_miscellaneous_information.pd

    Evaluating Activity for Hydrogen-Evolving Cobalt and Nickel Complexes at Elevated Pressures of Hydrogen and Carbon Monoxide

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    Molecular cobalt and nickel complexes are among the most promising homogeneous systems for electrocatalytic hydrogen evolution. However, there has been little exploration into the effect of gaseous co-additives such as CO and H_2, which may be present in operating hydrogen-evolving or carbon-dioxide reduction systems, on the performance of these molecular electrocatalysts. In this report, we investigate the electrocatalytic activity of six cobalt and nickel complexes supported by tetraazamacrocyclic or diazadiphosphacyclooctane ligands for the reduction of p-toluenesulfonic acid to hydrogen in acetonitrile under inert atmosphere and in the presence of CO and H_2. We present an elevated-pressure electrochemical apparatus capable of reaching CO and H_2 pressures of ca. 15–520 pounds per square inch (psia) (∼1–35 atm), and we use this apparatus to determine binding constants for CO addition for each catalyst and study the inhibition of the electrocatalysis as a function of CO and H_2 pressure. In the case of CO, the extent of catalytic inhibition is correlated to the binding constant, with the cobalt complexes showing a greater degree of catalyst inhibition compared to the nickel complexes. In the case of H2, no complex showed appreciable electrocatalytic inhibition even at H_2 pressures of ca. 500 psia

    Borazineâ CF3â Adducts for Rapid, Room Temperature, and Broad Scope Trifluoromethylation

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    A fluoroformâ derived borazine CF3â transfer reagent is used to effect rapid nucleophilic reactions in the absence of additives, within minutes at 25â °C. Inorganic electrophiles spanning seven groups of the periodic table can be trifluoromethylated in high yield, including transition metals used for catalytic trifluoromethylation. Organic electrophiles included (hetero)arenes, enabling Câ H and Câ X trifluoromethylation reactions. Mechanistic analysis supports a dissociative mechanism for CF3â transfer, and cation modification afforded a reagent with enhanced stability.Von Fluoroform abgeleitet wurde ein stabiles Reagenz für nukleophile Trifluormethylierungen anorganischer und organischer Elektrophile (E) bei Raumtemperatur. Das Reaktionsspektrum umfasst 18 anorganische Elemente, nucleophile aromatische Substitutionen sowie CF3â â Additionen an Carbonylverbindungen und Imine. Kinetische Studien sprechen für einen dissoziativen Mechanismus.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/141871/1/ange201711316-sup-0001-misc_information.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/141871/2/ange201711316.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/141871/3/ange201711316_am.pd

    Borazineâ CF3â Adducts for Rapid, Room Temperature, and Broad Scope Trifluoromethylation

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    A fluoroformâ derived borazine CF3â transfer reagent is used to effect rapid nucleophilic reactions in the absence of additives, within minutes at 25â °C. Inorganic electrophiles spanning seven groups of the periodic table can be trifluoromethylated in high yield, including transition metals used for catalytic trifluoromethylation. Organic electrophiles included (hetero)arenes, enabling Câ H and Câ X trifluoromethylation reactions. Mechanistic analysis supports a dissociative mechanism for CF3â transfer, and cation modification afforded a reagent with enhanced stability.A trifluoromethylating matter: A stable fluoroformâ derived reagent facilitates the nucleophilic trifluoromethylation of a broad array of inorganic and organic electrophiles (E) at room temperature. The reaction scope includes 18 inorganic elements, nucleophilic aromatic substitution, and CF3â addition to carbonyl and imine compounds. Kinetic analysis supports a dissociative mechanism.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/141342/1/anie201711316_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/141342/2/anie201711316.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/141342/3/anie201711316-sup-0001-misc_information.pd

    Reductive C−C Coupling from α,β‐Unsaturated Nitriles by Intercepting Keteniminates

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    We present an atom‐economic strategy to catalytically generate and intercept nitrile anion equivalents using hydrogen transfer catalysis. Addition of α,β‐unsaturated nitriles to a pincer‐based Ru−H complex affords structurally characterized κ‐N‐coordinated keteniminates by selective 1,4‐hydride transfer. When generated in situ under catalytic hydrogenation conditions, electrophilic addition to the keteniminate was achieved using anhydrides to provide α‐cyanoacetates in high yields. This work represents a new application of hydrogen transfer catalysis using α,β‐unsaturated nitriles for reductive C−C coupling reactions.Eine atomökonomische Strategie zur katalytischen Erzeugung und Verwendung von Nitrilanion‐Äquivalenten basiert auf Wasserstofftransferkatalyse. Die Addition von α,β‐ungesättigten Nitrilen an einen Ru‐H‐Pinzettenkomplex generiert durch selektiven 1,4‐Hydridtransfer Keteniminate, die in einer hydrierenden Acylierung eingesetzt wurden.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/149558/1/ange201904530_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/149558/2/ange201904530-sup-0001-misc_information.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/149558/3/ange201904530.pd

    Redox rich dicobalt macrocycles as templates for multi-electron transformations

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    Pyridazine-templated dicobalt macrocycles reversibly support five oxidation states with unusually positive Co^(II)/Co^I redox couples, and are also active proton reduction electrocatalysts

    Application of Multi-SNP Approaches Bayesian LASSO and AUC-RF to Detect Main Effects of Inflammatory-Gene Variants Associated with Bladder Cancer Risk

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    The relationship between inflammation and cancer is well established in several tumor types, including bladder cancer. We performed an association study between 886 inflammatory-gene variants and bladder cancer risk in 1,047 cases and 988 controls from the Spanish Bladder Cancer (SBC)/EPICURO Study. A preliminary exploration with the widely used univariate logistic regression approach did not identify any significant SNP after correcting for multiple testing. We further applied two more comprehensive methods to capture the complexity of bladder cancer genetic susceptibility: Bayesian Threshold LASSO (BTL), a regularized regression method, and AUC-Random Forest, a machine-learning algorithm. Both approaches explore the joint effect of markers. BTL analysis identified a signature of 37 SNPs in 34 genes showing an association with bladder cancer. AUC-RF detected an optimal predictive subset of 56 SNPs. 13 SNPs were identified by both methods in the total population. Using resources from the Texas Bladder Cancer study we were able to replicate 30% of the SNPs assessed. The associations between inflammatory SNPs and bladder cancer were reexamined among non-smokers to eliminate the effect of tobacco, one of the strongest and most prevalent environmental risk factor for this tumor. A 9 SNP-signature was detected by BTL. Here we report, for the first time, a set of SNP in inflammatory genes jointly associated with bladder cancer risk. These results highlight the importance of the complex structure of genetic susceptibility associated with cancer risk.The work was partially supported by the Fondo de Investigacion Sanitaria, Instituto de Salud Carlos III (G03/174, 00/0745, PI051436, PI061614, PI09-02102, G03/174 and Sara Borrell fellowship to ELM) and Ministry of Science and Innovation (MTM2008-06747-C02-02 and FPU fellowship award to VU), Spain; AGAUR-Generalitat de Catalunya (Grant 2009SGR-581); Fundaciola Maratode TV3; Red Tematica de Investigacion Cooperativa en Cancer (RTICC); Asociacion Espanola Contra el Cancer (AECC); EU-FP7-201663; and RO1-CA089715 and CA34627; the Spanish National Institute for Bioinformatics (www.inab.org); and by the Intramural Research Program of the Division of Cancer Epidemiology and Genetics, National Cancer Institute, USA. MD Anderson support for this project included U01 CA 127615 (XW); R01 CA 74880 (XW); P50 CA 91846 (XW, CPD); Betty B. Marcus Chair fund in Cancer Prevention (XW); UT Research Trust fund (XW) and R01 CA 131335 (JG)
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