Functional group metathesis is an emerging field in organic chemistry with promising synthetic applications. However, no complete mechanistic studies of these reactions have been reported to date, particularly regarding the nature key functional transfer mechanism. Unraveling mechanism transformations would not only allow for their further improvement but also lead design novel reactions. Herein, we describe our detailed nickel-catalyzed reaction between aryl methyl sulfides and nitriles,...

Herein, we report a nickel–1,2-bis(dicyclohexylphosphino)ethane (dcype) complex for the catalytic Buchwald–Hartwig amination of aryl thioethers. The protocol shows broad applicability with variety different functional groups tolerated under conditions. Extensive organometallic and kinetic studies support nickel(0)–nickel(II) pathway this transformation revealed oxidative addition as resting state cycle. All isolated intermediates have proven to be catalytically kinetically competent...

Abstract Nanoparticle sintering during catalytic reactions is a major cause for catalyst deactivation. Understanding its atomic-scale processes and finding strategies to reduce it of paramount scientific economic interest. Here, we report on the composition-dependent three-dimensional restructuring epitaxial platinum–rhodium alloy nanoparticles alumina carbon monoxide oxidation at 550 K near-atmospheric pressures employing in situ high-energy grazing incidence x-ray diffraction, online mass...

Herein, we demonstrate that ligand design enables the direct addition of acid chlorides across alkynes in a single step with complete atom economy to afford α,β-unsaturated chloride products. This carbochlorocarbonylation reaction, which proceeds through formal cleavage and reassembly C–COCl bonds, was developed explored for range alkynes. During course this work, formation synthetically useful cyclopentenones, C–H functionalization step, serendipitously observed at elevated temperatures....

Reductive elimination is the key bond-forming elementary step in many transition metal catalyzed reactions relevant to synthesis of pharmaceuticals, materials and fine chemicals. Metal electronics, ancillary ligand sterics complex coordination number have been identified as primary factors which affect rate reductive elimination, but their relative importance has not quantified. We report development a new class palladacycles used study these depth. Through kinetics, electrochemistry, DFT...

The past 20 years have seen an extensive implementation of nickel in homogeneous catalysis through the development unique reactivity not easily achievable by using noble transition metals. Many catalytic cycles propose Ni(I) complexes as potential reactive intermediates, yet scarcity nickel(I) precursors and lack a general, non-ligand-specific protocol for their synthesis hampered progress this field research. This has turn also limited access to novel, well-defined species new reactions....

Many methods report the scission of N–O bonds aromatic heterocycles and their subsequent functionalization. Oxidative addition is one presumed pathways through which bond activation with transition metals achieved. We first well-defined pathway (benz)isoxazole's oxidative addition. also provide control experiments, show that may be broken by strong inorganic reductants. These results highlight are susceptible to both reduction addition, has important implications for catalysis. Exploring...

25 nm thick Gd-doped ceria thin films were grown on yttria-stabilized zirconia (YSZ) substrates with (110) and (111) orientation by pulsed laser deposition to study both their crystalline structure interfacial stability. The characterized high-energy grazing incidence x-ray diffraction, reflectivity photoelectron spectroscopy before after annealing 1400 K under ultra-high vacuum (UHV) conditions. found be epitaxial the YSZ substrates, exhibiting good quality without defects like twinning,...

Abstract In the last twenty years, nickel has successfully imprinted its role in field of homogeneous catalysis as a valid and complementary alternative to palladium platinum catalysts. However, compared those, there are often many different available pathways due facile access intermediate oxidation states. Among them, Ni(I) been increasingly proposed key state multiple transformations. This had already suggested long time ago but only recently undergone renaissance with extensive ligand...

High-energy surface-sensitive x-ray diffraction (HESXRD) is a powerful high-energy photon technique (E > 70 keV) that has in recent years proven to allow fast data acquisition for the 3D structure determination of surfaces and nanoparticles under situ operando conditions. The use large-area detector facilitates direct collection nearly distortion-free patterns over wide $q$ range, including crystal truncation rods perpendicular surface reciprocal space maps from epitaxial nanoparticles,...

Oxidation induced dealloying of PdRh nanoparticles: Rh wins the oxidation race.

Fluorescein and rhodamine B modified mesoporous silica particles were synthesized by post-grafting co-condensation approaches. The materials exhibited different pore size distributions, particle shapes sizes. characterized nitrogen sorption, scanning electron microscopy fluorescence spectroscopy. Förster resonance energy transfer between the selected dye pair was explored for exposure to various concentrations of gaseous ammonia. A logarithmic increase in emission with increasing ammonia...

The interaction of carbon monoxide (CO) with graphene supported Ir cluster (Ir/graphene/Ir(111)) and a Ir(111) single crystal surface was studied by infrared reflection–adsorption spectroscopy (IRRAS). morphology characterized scanning tunneling microscopy density functional theory (DFT) calculations predicted the adsorption frequencies CO molecules on clusters. After exposing clean to at 195 K, one intense vibrational band is observed 2043 cm–1, which assigned top species. This shifts much...

Heteroepitaxial iridium thin films were deposited on (0001) sapphire substrates by means of molecular beam epitaxy, and subsequently, one monolayer graphene was synthesized chemical vapor deposition. The influence the growth parameters quality Ir films, as well graphene, investigated systematically low energy electron diffraction, x-ray reflectivity, Auger spectroscopy, scanning microscopy, atomic force microscopy. Our study reveals (111) oriented with high crystalline extremely surface...

A sequential Sonogashira coupling of a protected acetylene precursor with aryl halides (5) followed by pyrazolyl iodides ( 14) allows efficient access to the unsymmetrical aryl-heteroarylacetylene (8).Subsequent regioselective lithiation exchange dimethyl oxalate quench produced readily vicinal ketoesters (9) which show auxin effects in wide variety plant species.

Abstract Given the prevalence of molecules containing nitro groups in organic synthesis, innovative methods to expand reactivity this functional group are interest both industrial and academic settings. In report, a metal‐free intramolecular benzylic sp 3 C−H amination is disclosed using aryl compounds as nitrene precursors. Organosilicon reagent N , ’‐bis(trimethylsilyl)‐4,4’‐bipyridinylidene (Si‐DHBP) served an efficient reductant transformation, enabling situ generation species for...

Abstract As one of the most-consumed drugs worldwide, ibuprofen (IBU) reaches environment in considerable amounts as environmental pollutant, necessitating studies its further biotransformation potential removal mechanism. Therefore, we screened bacteria with known capabilities to degrade aromatic pollutants, belonging genera Bacillus , Priestia (formerly also ) Paenibacillus Mycobacterium and Cupriavidus for their ability transform ibuprofen. We identified five transformation products,...

Phosphine-stabilized monovalent nickel complexes play an important role in catalysis, either as catalytically active species or decomposition products. Most routes to access these are highly ligand specific rely on strong reducing agents. Our group recently disclosed a path nickel(I)–phenolate from bis(1,5-cyclooctadiene)nickel(0) (Ni(cod)2). Herein, we demonstrate this protocol's broad applicability by ligating wide range of mono- and bidentate phosphine ligands. We further show the...

New management practices must be developed to improve yam productivity. By allowing non-destructive analyses of important plant traits, image-based phenotyping techniques could help developing such practices. Our objective was determine the potential methods assess traits relevant for tuber yield formation in grown glasshouse and field. We took leaf pictures with consumer cameras. used numbers image pixels derive shoot biomass total surface calculated ‘triangular greenness index’ (TGI) which...

Management practices must be developed to improve yam production sustainability. Image-based phenotyping techniques could help developing such based on non-destructive analyses of important plant traits. Our objective was determine the potential image-based methods assess traits relevant for tuber yield formation in grown glasshouse and field. We took leaf pictures with consumer cameras. used numbers image pixels derive shoot biomass total surface calculated ‘triangular greenness...