Articles in 2018

Despite the many recent developments in iron-catalysed cross-couplings, the mechanistic understanding of these reactions is lacking compared to the more studied palladium and nickel variants. Here, the authors find that during iron-catalysed Negishi reactions the diphosphine ligand predominately binds to the zinc—rather than the iron—centre.

Carbon-based single-atom catalysts usually rely on nitrogen co-doping to stabilize the single metal atoms as metal–N₄ moieties. Now, Wei, Yao and colleagues make use of operando techniques to show that under alkaline hydrogen evolution reaction conditions the Co–N₄ active site undergoes structural distortion to a HO–Co–N₂ configuration.

Silicon–hydride materials are attractive candidates for the photoreduction of carbon dioxide into fuels, although they have only worked stoichiometrically so far. Now, Ozin and co-workers show how decorating silicon nanosheets with palladium nanoparticles renders the process catalytic.

Single-atom catalysts are receiving much attention, but insights into their active sites or the differences in reactivity with conventional nanoparticles are still controversial. Now, operando studies on CO oxidation with Ir/MgAl₂O₄ accompanied by computational investigations reveal important features of this class of catalyst.

The use of electrochemistry in asymmetric catalysis can prove challenging, not least due to the difficulty of achieving chemo- and stereoselectivity in combination with very reactive electrochemically generated intermediates. Here, catalytic asymmetric electrosynthesis is reported for the synthesis of 1,4-dicarbonyl compounds with high enantiomeric excess, including compounds with all-carbon quaternary stereocentres. The chiral-at-metal catalyst activates the substrate towards anodic oxidation in addition to controlling the enantioselectivity of the process.

Reusable catalysts based on earth-abundant metals could offer inexpensive and sustainable routes in organic synthesis. Here a nickel catalyst—formed by pyrolysis of a nickel complex on a γ-Al₂O₃ support—is shown to be highly active for synthesis of primary amines via reductive amination. The catalyst operates with aqueous ammonia and either aldehydes or ketones, tolerating a wide range of functional groups.

The electroreduction of carbon dioxide to formate represents a desirable strategy for the production of fuels and commodity chemicals. Now, guided by density functional theory, Cui and colleagues report CuSn₃ alloys that exhibit high activity and selectivity for formate production from CO₂ electroreduction at potentials as low as −0.5 V versus RHE.

Copper-based catalysts, especially the so-called oxide-derived copper, are capable of producing multicarbon species from electrochemical CO₂ reduction. However, little is known about their active sites despite intensive research efforts. Now, Lum and Ager show that oxide-derived copper catalysts have three distinct product-specific sites for the formation of C₂₊ chemicals, unlike polycrystalline copper or (111)- and (100)-oriented copper films which show no evidence of product specific sites.

Single-atom catalysts are very attractive due to their ability to maintain high activities at the lowest possible precious metal loading. Here, a double transition metal MXene that effectively anchors single Pt atoms is reported, and exhibits superior performance and stability towards the hydrogen evolution reaction.

Predicting highly enantioselective ligands for a given asymmetric catalytic reaction is very challenging, but could greatly reduce the need for high-throughput, trial-and-error experimentation. Here, the authors report a freely available, automated tool to identify appropriate chiral ligands for given substrates in asymmetric catalysis.

Unlike the more common C–H functionalization, methods for the functionalization of C–C bonds are scarce. Here, Ackermann and co-workers show that an inexpensive manganese catalyst is capable of selectively activating C–C bonds for alkylations, alkenylations, and allylations in water.

Catalysts are dynamic species, whose structure can change over the course of a reaction. Here, structural changes are mapped for cobalt–palladium nanoparticles during CO oxidation, showing a reconstruction to CoO_x on palladium surfaces. Furthermore, the composition-dependent reconstruction can be correlated with the trend in catalytic activity.

One of the major routes for the use of CO₂ in chemical production is the formation of carbonates via cycloaddition of CO₂ to epoxides. This work uses a range of experimental and computational techniques to map out the elusive key intermediates in this process.

Mupirocin is a clinically important antibiotic, but the biosynthesis of its tetrahydropyran moiety—an oxygen heterocycle essential for its bioactivity—has remained elusive. Here, Willis, Crump and co-workers report an enzymatic reaction cascade catalysing this ring formation from a non-activated C–H bond.

The function of putative bacterial vitamin K-dependent carboxylases (VKDCs) has so far been uncertain. Now, Micklefield and co-workers show that a bacterial VKDC orthologue is involved in the biosynthesis of the antibiotic malonomycin, generating an unusual malonic acid moiety that is essential for its biological activity.

The nature of the active sites of molybdenum trioxide and molybdenum carbide, two related catalysts with great potential for hydrodeoxygenation reactions, is still under debate. Now, a comparative operando near-ambient-pressure XPS study during hydrodeoxygenation of anisole reveals important differences between these two materials.

Methanol synthesis from methane is a promising route to valorize this abundant natural gas, but existing thermal processes require harsh reaction conditions. Now, a photocatalytic approach based on TiO₂-supported iron oxide species is described, which affords methanol in high yield and selectivity at ambient conditions.

Catalytic studies on single crystals are very insightful, but it is often difficult to extend their conclusions to an actual catalytic process due to gaps in the experimental conditions. Now, Madix and co-workers report a method to bridge these gaps using the oxidative coupling of methanol on gold as an example.

The reason for the high water-oxidation activity of Ni(Fe)O_xH_y catalysts in alkaline electrolyte is not yet well understood. Now, Chorkendorff and co-workers report that oxygen evolution is limited to the near-surface region by measuring the activity trends of mass-selected NiFe nanoparticles.

The production of higher alcohols is very valuable because of their high volumetric energy density. Now, Sargent, Sinton and co-workers report the design of copper nanoparticles with tailored nanocavities that promote n-propanol formation by the coupling of C2 and C1 intermediates inside the cavity.