Biomimetic Catalytic Remote Desaturation of Aliphatic Alcohols.

Herein we present photoinduced cobaloxime-catalyzed selective remote desaturation of aliphatic alcohols. This transformation, which proceeds efficiently at room temperature, facilitates the synthesis of valuable cyclic and acyclic allylic and homoallylic alcohols from readily available saturated aliphatic alcohols. Remarkably, this method obviates the need for external oxidants, noble metal catalysts, and phosphine ligands.

Interfacial Engineering of MoS via Boron-Doping for Electrochemical N-to-NH Conversion.

The electrocatalytic synthesis of ammonia (NH) through the nitrogen reduction reaction (NRR) under ambient temperature and pressure is emerging as an alternative approach to the conventional Haber-Bosch process. However, it remains a significant challenge due to poor kinetics, low nitrogen (N) solubility in aqueous electrolytes, and the competing hydrogen evolution reaction (HER), which can significantly impact NH production rates and Faradaic efficiency (FE). Herein, a rationally designed boron-doped molybdenum sulfide (B-Mo-MoS) electrocatalyst is reported that effectively enhances N reduction to  NH with an onset potential of -0.

Understanding the coupling of non-metallic heteroatoms to CO from a Conceptual DFT perspective.

Context: A Conceptual DFT (CDFT) study has been carry out to analyse the coupling reactions of the simplest amine (CHNH), alcohol (CHOH), and thiol (CHSH) compounds with CO to form the corresponding adducts CHNHCOH, CHOCOH, and CHSCOH. The reaction mechanism takes place in a single step comprising two chemical events: nucleophilic attack of the non-metallic heteroatoms to CO followed by hydrogen atom transfer (HAT). According to our calculations, the participation of an additional nucleophilic molecule as HAT assistant entails important decreases in activation electronic energies.

Biomimetic Photoexcited Cobaloxime Catalysis in Organic Synthesis.

Drawing inspiration from nature has long been a cornerstone of chemical innovation, with natural systems offering a wealth of untapped potential for discovery. In this minireview, we delve into the burgeoning field of cobaloxime catalysis in organic synthesis, which mimics the catalytic activity of the natural organometallic alkylcobalamine enzymes. Our focus lies on elucidating the latest advancements in this area, as well as delineating the primary mechanistic pathways at play.

Concluding remarks: Sustainable nitrogen activation - are we there yet?

The activation of dinitrogen as a fundamental step in reactions to produce nitrogen compounds, including ammonia and nitrates, has a cornerstone role in chemistry. Bringing together research from disparate fields where this can be achieved sustainably, this seeks to build connections between approaches that can stimulate further advances. In this paper we set out to provide an overview of these different approaches and their commonalities.

Photoexcited cobalt catalysed -selective alkyl Heck reaction.

Herein, we report an intramolecular -selective Heck reaction of iodomethylsilyl ethers of phenols and alkenols. The reaction leads to the formation of seven- and eight-membered siloxycycles in excellent yields, which could be further converted into the corresponding allylic alcohols upon oxidation. Thus, this method could be used for the selective ()-hydroxymethylation of -hydroxystyrenes and alkenols.

Effect of Ligands on the Stability of Gold Nanoclusters.

Gold nanoclusters (AuNCs) are atomic architectures that can be precisely tailored for catalytic applications. In this work, we studied two benchmark AuNCs, Au(SR) and Au(SR), covered by aromatic and aliphatic ligands to envision how the 3D structure of the ligand impacts the stability of the nanomaterial. Surprisingly, we found that increasing the alkanethiol length has a poor or null effect on the stability of the AuNCs, a trend opposite to that on Au(111) surfaces.

In silico design of novel NRR electrocatalysts: cobalt-molybdenum alloys.

Metals are amongst the most efficient developed electrocatalysts for nitrogen reduction reaction (NRR) with iron and ruthenium presenting the best catalytic indicators. However, the potential use of metal alloys as NRR electrocatalysts is still underdeveloped. While Co has demonstrated poor electrocatalytic activity for NRR, alloying Co with Mo exhibits an improvement in both N physisorption and the stabilisation of the elusive NH as the first reduced intermediate species.

Conversion of racemic alcohols to optically pure amine precursors enabled by catalyst dynamic kinetic resolution: experiment and computation.

An unprecedented base metal catalysed asymmetric synthesis of α-chiral amine precursors from racemic alcohols is reported. This redox-neutral reaction utilises a bench-stable manganese complex and Ellman's sulfinamide as a versatile ammonia surrogate. DFT calculations explain the unusual finding of the highly stereoselective transformation enabled by a catalyst that undergoes an unusual dynamic kinetic resolution.

Manganese-Catalyzed Regioselective Dehydrogenative C- versus N-Alkylation Enabled by a Solvent Switch: Experiment and Computation.

The first base metal-catalyzed regioselective dehydrogenative alkylation of indolines using readily available alcohols as the alkylating reagent is reported. A single air- and moisture-stable manganese catalyst provides access to either C- or N-alkylated indoles depending on the solvent used. Mechanistic studies indicate that the reaction takes place through a combined acceptorless dehydrogenation and hydrogen autotransfer strategy.

Stabilisation of dianion dimers trapped inside cyanostar macrocycles.

Interanionic H-bonds (IAHBs) are unfavourable interactions in the gas phase becoming favoured when anions are in solution. Dianion dimers are also susceptible to being trapped inside the cavities of cyanostar (CS) macrocycles, and thus, the formation of 2 : 2 anion : cyanostar aggregates is mainly supported by three kinds of interactions: IAHBs between the dianions, π-π stacking between the confronted cyanostars, and the presence of an intricate network of multiple C(sp)HO H-bonds between cyanostar ligands and the anionic moieties. An analysis of the interaction energies supported by NBO reveals a slight cooperative effect of the CSs on the IAHB stabilisation.

A Conceptual DFT Study of Phosphonate Dimers: Dianions Supported by H-Bonds.

A conceptual DFT study of the dissociation of anionic and neutral phosphonate dimers has been carried out. In addition, the dianion complexes have been studied in the presence of two solvents, water and tetrahydrofuran. The dissociation of the dianion complexes in the gas phase and in solution present a maximum along the reaction coordinate that is not present in the neutral-neutral and anion-neutral complexes.

Liquefied Sunshine: Transforming Renewables into Fertilizers and Energy Carriers with Electromaterials.

It has become apparent that renewable energy sources are plentiful in many, often remote, parts of the world, such that storing and transporting that energy has become the key challenge. For long-distance transportation by pipeline and bulk tanker, a liquid form of energy carrier is ideal, focusing attention on liquid hydrogen and ammonia. Development of high-activity and selectivity electrocatalyst materials to produce these energy carriers by reductive electrochemistry has therefore become an important area of research.

Diastereoselective diazenyl formation: the key for manganese-catalysed alcohol conversion into (E)-alkenes.

The proposed reaction mechanism for the unprecedented direct transformation of primary alcohols into alkenes catalysed by Mn(i)-PNP complexes consists of two cycles. First, the acceptorless dehydrogenation of the alcohol into aldehyde is produced via a concerted mechanism. Secondly, in an excess of hydrazine, hydrazone is formed and reacts with the aldehyde to produce olefins.

Quantifying electronic similarities between NHC-gold(i) complexes and their isolobal imidazolium precursors.

A series of NHC-gold(i) (NHC = N-heterocyclic carbene) complexes has been studied by DFT calculations, enabling comparison of electronic and NMR behaviour with related protonated and free NHC molecules. Based on calculations, the NMR resonances of the carbenic C2 carbon atom in [Au(NHC)(Cl)] and [NHC(H)][Cl] exhibit increased shielding when compared to the free N-heterocyclic carbenes by an average of 46.6 ± 2.

Regression analysis of properties of [Au(IPr)(CHR)] complexes.

New [Au(IPr)(CHR)] complexes have been synthesised through protonolysis reactions of [Au(IPr)(OH)] with moderately acidic substrates, CHR. An array of spectroscopic (IR and NMR), structural (X-ray), electronic (DFT) and experimental (reactivity) parameters was collected to quantify the variation in stereoelectronic properties of these new and previously reported [Au(IPr)(CHR)] complexes. Variation of the R substituents on the carbanion ligands (CHR) was found to have a crucial impact on parameters characterising the resulting gold complexes.

Hydrogen Evolution in [NiFe] Hydrogenases: A Case of Heterolytic Approach between Proton and Hydride.

The mechanism for Hydrogen Evolution Reaction (HER) in [NiFe] hydrogenase enzymes distinguishes them from inorganic catalysts. The first H/e pair injected to the active site of the hydrogenases transforms into hydride, while the second H/e pair injection leads to the formation of the H/H pair both binding to the active site. The two opposite charged hydrogens heterolytically approach each other in order to form dihydrogen (H), which is enhanced by the Coulomb force.

Manganese-Catalyzed Multicomponent Synthesis of Pyrroles through Acceptorless Dehydrogenation Hydrogen Autotransfer Catalysis: Experiment and Computation.

A new base metal catalyzed sustainable multicomponent synthesis of pyrroles from readily available substrates is reported. The developed protocol utilizes an air- and moisture-stable catalyst system and enables the replacement of themutagenic α-haloketones with readily abundant 1,2-diols. Moreover, the presented method is catalytic in base and the sole byproducts of this transformation are water and hydrogen gas.

Single-Site Molybdenum on Solid Support Materials for Catalytic Hydrogenation of N -into-NH.

Very stable in operando and low-loaded atomic molybdenum on solid-support materials have been prepared and tested to be catalytically active for N -into-NH hydrogenation. Ammonia synthesis is reported at atmospheric pressure and 400 °C with NH rates of approximately 1.3×10  μmol h  g using a well-defined Mo-hydride grafted on silica (SiO ).

Hydrogenation of CO -Derived Carbonates and Polycarbonates to Methanol and Diols by Metal-Ligand Cooperative Manganese Catalysis.

The first base-metal-catalysed hydrogenation of CO -derived carbonates to alcohols is presented. The reaction proceeds under mild conditions in the presence of a well-defined manganese complex with a loading as low as 0.25 mol %.

Energy-Efficient Nitrogen Reduction to Ammonia at Low Overpotential in Aqueous Electrolyte under Ambient Conditions.

The electrochemical nitrogen reduction reaction (NRR) under ambient conditions is a promising alternative to the traditional energy-intensive Haber-Bosch process to produce NH . The challenge is to achieve a sufficient energy efficiency, yield rate, and selectivity to make the process practical. Here, we demonstrate that Ru nanoparticles (NPs) enable NRR in 0.

Hydrogen bonding effect between active site and protein environment on catalysis performance in H-producing [NiFe] hydrogenases.

The interaction between the active site and the surrounding protein environment plays a fundamental role in the hydrogen evolution reaction (HER) in [NiFe] hydrogenases. Our density functional theory (DFT) findings demonstrate that the reaction Gibbs free energy required for the rate determining step decreases by 7.1 kcal mol when the surrounding protein environment is taken into account, which is chiefly due to free energy decreases for the two H/e addition steps (the so-called Ni-SIa to I1, and Ni-C to Ni-R), being the largest thermodynamic impediments of the whole reaction.

Experimental and Computational Study of an Unexpected Iron-Catalyzed Carboetherification by Cooperative Metal and Ligand Substrate Interaction and Proton Shuttling.

An iron-catalyzed cycloisomerization of allenols to deoxygenated pyranose glycals has been developed. Combined experimental and computational studies show that the iron complex exhibits a dual catalytic role in that the non-innocent cyclopentadienone ligand acts as proton shuttle by initial hydrogen abstraction from the alcohol and by facilitating protonation and deprotonation events in the isomerization and demetalation steps. Molecular orbital analysis provides insight into the unexpected and selective formation of the 3,4-dihydro-2H-pyran.

Feasibility of N Binding and Reduction to Ammonia on Fe-Deposited MoS 2D Sheets: A DFT Study.

Based on the structure of the nitrogenase FeMo cofactor (FeMoco), it is reported that Fe deposited on MoS 2D sheets exhibits high selectivity towards the spontaneous fixation of N against chemisorption of CO and H O. DFT predictions also indicate the ability of this material to convert N into NH with a maximum energy input of 1.02 eV as an activation barrier for the first proton-electron pair transfer.