Transfer hydrogenation of ketones catalyzed by new rhodium and iridium complexes of aminophosphine containing cyclohexyl moiety and photosensing behaviors of rhodium and iridium based devices

Nickel-catalyzed transfer hydrogenation of ketones using ethanol as a solvent and a hydrogen donor

We report a nickel(0)-catalyzed direct transfer hydrogenation (TH) of a variety of alkyl–aryl, diaryl, and aliphatic ketones with ethanol.

Optical properties and device characteristics of 2-(antipyrin-4-ylhydrazono)-2-(4-nitrophenyl)acetonitrile thin films for photodiode applications

2-(Antipyrin-4-ylhydrazono)-2-(4-nitrophenyl)acetonitrile (AHNA) films were deposited via thermal evaporation technique. The optical properties of AHNA films and electrical characteristics of Au/AHNA/n-Si/Au heterojunction diode have been reported. The optical properties of AHNA films were investigated using the spectrophotometric measurements of optical transmittance and reflectance over spectral range 190-2500 nm. The films have indirect allowed optical band gap of 3.6 eV. The refractive index of the films was calculated and the dispersion parameters of the films were determined on the light of the single oscillator model. The electrical properties of Au/AHNA/n-Si/Au heterojunction diode were studied in terms of current-voltage characteristics. The device showed rectification behaviour with a rectification ratio of 100 at ±1 V. The conduction mechanisms and diode parameters such as ideality factor, barrier height and series resistance of the device were determined. The device under illumination showed photovoltaic properties. The short circuit current and open circuit voltage were found to be function of illumination intensity. The device satisfies the conditions to be used as photodiode.

Mechanistic and Kinetic Studies of the Direct Alkylation of Benzylic Amines: A Formal C(sp3)-H Activation Proceeds Actually via a C(sp2)-H Activation Pathway

Mechanistic investigations of a Rh(I)-catalyzed direct C-H alkylation of benzylic amines with alkenes, formally an C(sp3)-H activation, reveal this reaction to proceed via imine intermediates and, hence, via C(sp2)-H activation. The reaction shows a primary kinetic isotope effect of 4.3 at the benzylic C-H position together with a reversible H-D exchange at the same position, which indicates that there are at least two distinct steps in which the corresponding C-H bonds are broken. The imine intermediates are shown to be converted to the final product under the reaction conditions, and a time course analysis of the alkylated imine intermediate shows that it is formed before the final amine product in the course of the reaction.

Synthesis and structure of trinuclear W3S4 clusters bearing aminophosphine ligands and their reactivity toward halides and pseudohalides

The aminophosphine ligand (2-aminoethyl)diphenylphosphine (edpp) has been coordinated to the W3(μ-S)(μ-S)3 cluster unit to afford trimetallic complex [W3S4Br3(edpp)3](+) (1(+)) in a one-step synthesis process with high yields. Related [W3S4X3(edpp)3](+) clusters (X = F(-), Cl(-), NCS(-); 2(+)-4(+)) have been isolated by treating 1(+) with the corresponding halide or pseudohalide salt. The structure of complexes 1(+) to 4(+) contains an incomplete W3S4 cubane-type cluster unit, and only one of the possible isomers is formed: the one with the phosphorus atoms trans to the capping sulfur and the amino groups trans to the bridging sulphurs. The remaining coordination position on each metal is occupied by X. Detailed studies using stopped-flow, (31)P{(1)H} NMR, and ESI-MS have been carried out in order to understand the solution behavior and the kinetics of interconversion among species 1(+), 2(+), 3(+), and 4(+) in solution. Density functional theory (DFT) calculations have been also carried out on the reactions of cluster 1(+) with the different anions. The whole set of experimental and theoretical data indicate that the actual mechanism of substitutions in these clusters is strongly dependent on the nature of the leaving and entering anions. The interaction between an entering F(-) and the amino group coordinated to the adjacent metal have also been found to be especially relevant to the kinetics of these reactions.

Transfer hydrogenation of unsaturated bonds in the absence of base additives catalyzed by a cobalt-based heterogeneous catalyst

A novel non-noble Co@C–N system for catalytic transfer hydrogenation reactions is developed. The heterogeneous Co@C–N catalysts are highly active and selective in the hydrogenation of a variety of unsaturated bonds with isopropanol in the absence of base additives.

A conjugated ketone as a catalyst in alcohol amination reactions under transition-metal and hetero-atom free conditions

A molecular-defined conjugated ketone can be an active catalyst for alcohol amination reactions with up to 98% isolated yields for the desired products.