Selective Hydrogenation of Nitriles to Secondary Imines Catalyzed by an Iron Pincer Complex

Selective hydrogenation of nitriles to secondary imines catalyzed by an iron complex, the pincer complex (iPr-PNP)­Fe­(H)­Br­(CO), in the presence of catalytic base, is reported. A wide range of (hetero)­aromatic and aliphatic nitriles are hydrogenated to the corresponding secondary imines under mild conditions

Homogeneous Hydrogenation of Nitriles Catalyzed by Molybdenum and Tungsten Amides

Low-valent molybdenum and tungsten amides M­(NO)­(CO)­(PNP) {M = Mo, <b>1a</b>; W, <b>1b</b>; PNP = N­(CH₂CH₂P^<i>i</i>Pr₂)₂} were found to be active catalysts for the hydrogenation of various nitriles to the corresponding imines, primary amines, and N-substituted imines with high selectivity for the latter type of product. A wide range of p- and m-substituted aromatic nitriles<i>p</i>-methyl, <i>p</i>-methoxy, <i>p</i>-bromobenzonitriles; 3-trifluoromethylbenzonitrile, m- and p-disubstituted benzonitrile; the heterocyclic 2-thiophencarbonitrile; and the aliphatic nitriles cyclohexylcarbonitrile and benzylcyanidecould be hydrogenated at 140 °C and 60 bar H₂ in THF with high yields. TOFs were found to be between 0.4 and 36 h^–1

Normal and Anomalous Diffusion: An Analytical Study Based on Quantum Collision Dynamics and Boltzmann Transport Theory

Diffusion, an emergent nonequilibrium transport phenomenon, is a nontrivial manifestation of the correlation between the microscopic dynamics of individual molecules and their statistical behavior observed in experiments. We present a thorough investigation of this viewpoint using the mathematical tools of quantum scattering, within the framework of Boltzmann transport theory. In particular, we ask: (a) How and when does a normal diffusive transport become anomalous? (b) What physical attribute of the system is conceptually useful to faithfully rationalize large variations in the coefficient of normal diffusion, observed particularly within the dynamical environment of biological cells? To characterize the diffusive transport, we introduce, analogous to continuous phase transitions, the curvature of the mean square displacement as an order parameter and use the notion of quantum scattering length, which measures the effective interactions between the diffusing molecules and the surrounding, to define a tuning variable, η. We show that the curvature signature conveniently differentiates the normal diffusion regime from the superdiffusion and subdiffusion regimes and the critical point, η = η_<i>c</i>, unambiguously determines the coefficient of normal diffusion. To solve the Boltzmann equation analytically, we use a quantum mechanical expression for the scattering amplitude in the Boltzmann collision term and obtain a general expression for the effective linear collision operator, useful for a variety of transport studies. We also demonstrate that the scattering length is a useful dynamical characteristic to rationalize experimental observations on diffusive transport in complex systems. We assess the numerical accuracy of the present work with representative experimental results on diffusion processes in biological systems. Furthermore, we advance the idea of temperature-dependent effective voltage (of the order of 1 μV or less in a biological environment, for example) as a dynamical cause of the perpetual molecular movement, which eventually manifests as an ordered motion, called the diffusion

Manganese-Catalyzed Direct Deoxygenation of Primary Alcohols

Deoxygenation of alcohols is an important tool in the repertoire of defunctionalization methods in modern synthetic chemistry. We report the base-metal-catalyzed direct deoxygenation of benzylic and aliphatic primary alcohols via oxidative dehydrogenation/Wolff–Kishner reduction. The reaction is catalyzed by a well-defined PNP pincer complex of Earth-abundant manganese, evolving H₂, N₂, and water as the only byproducts

Highly Efficient Large Bite Angle Diphosphine Substituted Molybdenum Catalyst for Hydrosilylation

Treatment of the complex Mo­(NO)­Cl₃(NCMe)₂ with the large bite angle diphosphine, 2,2′-bis­(di­phenyl­phos­phino)­diphenylether (DPEphos) afforded the dinuclear species [Mo­(NO)­(P∩P)­Cl₂]₂[μCl]₂ (P∩P = DPEphos = (Ph₂PC₆H₄)₂O (<b>1</b>). <b>1</b> could be reduced in the presence of Zn and MeCN to the cationic complex [Mo­(NO)­(P∩P)­(NCMe)₃]⁺[Zn₂Cl₆]^2–_1/2 (<b>2</b>). In a metathetical reaction the [Zn₂Cl₆]^2–_1/2 counteranion was replaced with NaBAr^F₄ (BAr^F₄ = [B­{3,5-(CF₃)₂C₆H₃}₄]) to obtain the [BAr^F₄]⁻ salt [Mo­(NO)­(P∩P)­(NCMe)₃]⁺[BAr^F₄]⁻ (<b>3</b>). <b>3</b> was found to catalyze hydrosilylations of various <i>para</i> substituted benzaldehydes, cyclohexanecarboxaldehyde, 2-thiophenecarboxaldehyde, and 2-furfural at 120 °C. A screening of silanes revealed primary and secondary aromatic silanes to be most effective in the catalytic hydrosilylation with <b>3</b>. Also ketones could be hydrosilylated at room temperature using <b>3</b> and PhMeSiH₂. A maximum turnover frequency (TOF) of 3.2 × 10⁴ h^–1 at 120 °C and a TOF of 4400 h^–1 was obtained at room temperature for the hydrosilylation of 4-methoxyacetophenone using PhMeSiH₂ in the presence of <b>3</b>. Kinetic studies revealed the reaction rate to be first order with respect to the catalyst and silane concentrations and zero order with respect to the substrate concentrations. A Hammett study for various <i>para</i> substituted acetophenones showed linear correlations with negative ρ values of −1.14 at 120 °C and −3.18 at room temperature

Manganese Catalyzed α‑Olefination of Nitriles by Primary Alcohols

Catalytic α-olefination of nitriles using primary alcohols, via dehydrogenative coupling of alcohols with nitriles, is presented. The reaction is catalyzed by a pincer complex of an earth-abundant metal (manganese), in the absence of any additives, base, or hydrogen acceptor, liberating dihydrogen and water as the only byproducts

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<p>Probabilities for top level nodes for Scenario 4.</p

Customer service attributes considered in the survey.

<p>Customer service attributes considered in the survey.</p

Analysis results for Scenario 5.

<p>Analysis results for Scenario 5.</p

Initial probability values for top level nodes.

<p>Initial probability values for top level nodes.</p