One-Step Esterification of Phosphoric, Phosphonic and Phosphinic Acids with Organosilicates: Phosphorus Chemical Recycling of Sewage Waste.

Global concerns regarding the depletion and strategic importance of phosphorus resources have increased demand for the recovery and recycling. However, waste-derived phosphorus compounds, primarily as chemically inert phosphoric acid or its salts, present a challenge to their direct conversion into high-value chemicals. We aimed to develop an innovative technology that utilizes the large quantities of sewage waste, bypasses the use of white phosphorus, and enables esterification of phosphoric acid to produce widely applicable phosphate triesters.

A DFT Mechanistic Study on the Aza-Aldol Reaction of Boron Aza-Enolates: Relative Stability of Six-Membered Transition State and Its Relevance to the Coordination Mode of the Leaving Group.

The mechanism of the aza-aldol reaction between boron aza-enolate and benzaldehyde is investigated by using density functional theory calculations. The result shows that the - isomer is preferentially formed, consistent with experimental observations. The six-membered ring transition state (TS) with the boat form leads to the isomer, while the more unstable chair TS does to the isomer.

Photoinduced Enantioselective Triplet Radical Reaction on Metal: Copper-Catalyzed Conjugate Addition of Acylsilanes to α,β-Unsaturated Ketones and Aldehydes.

A photoinduced copper-catalyzed enantioselective conjugate addition of acylsilanes has been developed. The conjugate acylation of α,β-unsaturated ketones and aldehydes was promoted by a copper(I)/chiral NHC catalyst under visible-light irradiation for synthesizing various 2-substituted 1,4-dicarbonyl compounds in enantioenriched forms. Mechanistic studies combining experiments and quantum chemical calculations indicated a reaction mechanism involving copper-to-acyl charge transfer (i.

Exploring Catalytic Intermediates in Pd-Catalyzed Aerobic Oxidative Amination of 1,3-Dienes: Multiple Metal Interactions of the Palladium Nanoclusters.

Metal nanoclusters (NCs) have unique properties because of their small size, which makes them useful as catalysts in reactions like cross-coupling. Pd-catalyzed oxidative amination, which involves dehydrogenative C-N bond formation, uses Pd complexes as the active species. It is known that the catalytic conditions involve the formation of Pd(0) species from Pd NCs, but the precise role of Pd NCs in the transformations has not been established.

Characterization of changes in the electronic structure of platinum sub-nanoclusters supported on graphene induced by oxygen adsorption.

As the sizes of noble metal catalysts, such as platinum, have been successfully minimized, fundamental insights into the electronic properties of metal sub-nanoclusters are increasingly sought for optimizing their catalytic performance. However, it is difficult to rationalize the catalytic activities of metal sub-nanoclusters owing to their more complex electronic structure compared with those of small molecules and bulky solids. In this study, the adsorption of molecular oxygen on a Pt sub-nanocluster supported on a graphene layer was analyzed using density functional theory.

Mitigating the Poisoning Effect of Formate during CO Hydrogenation to Methanol over Co-Containing Dual-Atom Oxide Catalysts.

During the hydrogenation of CO to methanol over mixed-oxide catalysts, the strong adsorption of CO and formate poses a barrier for H dissociation, limiting methanol selectivity and productivity. Here we show that by using Co-containing dual-atom oxide catalysts, the poisoning effect can be countered by separating the site for H dissociation and the adsorption of intermediates. We synthesized a Co- and In-doped ZrO catalyst (Co-In-ZrO) containing atomically dispersed Co and In species.

A Multiconfigurational Wave Function Theoretical Study on Electronic Structure and Magnetic Susceptibility of Dilanthanide Single Molecule Magnet.

Single molecule magnets (SMMs) have been a promising material for next-generation high-density information storage and molecular spintronics. N-bridged dilanthanide complexes, {[(MeSi)N]Ln(THF)(μ-η:η-N)(THF)Ln[(MeSi)N]}, exhibit high blocking temperatures and have been one of the promising candidates for future application. Rational understanding should be established between the magnetic properties and electronic structure.

Dimethyl carbonate synthesis from CO and methanol over CeO: elucidating the surface intermediates and oxygen vacancy-assisted reaction mechanism.

Surface intermediate species and oxygen vacancy-assisted mechanism over CeO catalyst in the direct dimethyl carbonate (DMC) synthesis from carbon dioxide and methanol are suggested by means of transient spectroscopic methodologies in conjunction with multivariate spectral analysis. How the two reactants, CO and methanol, interact with the CeO surface and how they form decisive surface intermediates leading to DMC are unraveled by DFT-based molecular dynamics simulation by precise statistical sampling of various configurations of surface states and intermediates. The atomistic simulations and uncovered stability of different intermediate states perfectly explain the unique DMC formation profile experimentally observed upon transient operations, strongly supporting the proposed oxygen vacancy-assisted reaction mechanism.

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Dynamic behavior of intermediate adsorbates, such as diffusion, spillover, and reverse spillover, has a strong influence on the catalytic performance in oxide-supported metal catalysts. However, it is challenging to elucidate how the intermediate adsorbates move on the catalyst surface and find active sites to give the corresponding products. In this study, the effect of the dynamic behavior of methoxy intermediate on methanol decomposition on a Pt/TiO(110) surface has been clarified by combination of scanning tunneling microscopy (STM), temperature-programmed desorption (TPD), and density functional theory (DFT) calculations.

DFT insight into metals and ligands substitution effects on reactivity of phenoxy-imine catalysts for ethylene polymerization.

The reaction mechanism of ethylene (ET) polymerization catalyzed by the phenoxy-imine (FI) ligands using DFT calculations was studied. Among five possible isomers, isomer A which has an octahedral geometry and a (cis-N/trans-O/cis-Cl) arrangement is the most stable pre-reaction Ti-FI dichloride complex. The isomer A can be activated by MAO to form the active catalyst and the active form was used for the study of the mechanism for Ti-FI.

Highly Enantioselective Radical Cation [2 + 2] and [4 + 2] Cycloadditions by Chiral Iron(III) Photoredox Catalysis.

Radical cations show a unique reactivity that is fundamentally different from that of conventional cations and have thus attracted considerable attention as alternative cationic intermediates for novel types of organic reactions. However, asymmetric catalysis to promote enantioselective radical cation reactions remains a major challenge in contemporary organic synthesis. Here, we report that the judicious design of an ion pair consisting of a radical cation and a chiral counteranion induces an excellent level of enantioselectivity.

Optimization of General Molecular Properties in the Equilibrium Geometry Using Quantum Alchemy: An Inverse Molecular Design Approach.

Inverse molecular design allows the optimization of molecules in chemical space and is promising for accelerating the development of functional molecules and materials. To design realistic molecules, it is necessary to consider geometric stability during optimization. In this work, we introduce an inverse design method that optimizes molecular properties by changing the chemical composition in the equilibrium geometry.

Paddle-Wheel Dirhodium Complexes Bearing Bulky Carboxylate Ligands: Synthesis and Catalysis in Carbene Insertion Reactions.

Dirhodium complexes bearing bulky carboxylate ligands are synthesized and characterized. The steric bulk of carboxylate ligands could affect the reaction selectivity in Rh-catalyzed intramolecular reactions: Rh catalysts with bulky carboxylate ligands provided five-membered ring products preferentially via the insertion into a carbon-hydrogen bond. Meanwhile, six-membered ring products were obtained using conventional Rh catalysts via the insertion of a carbon-carbon double bond.

First-principles study on unidirectional proton transfer on anatase TiO (101) surface induced by external electric fields.

The electric field (EF) effect on hydrogen or proton transfer (PT) hydroxyl groups on an anatase TiO (101) surface is examined using first-principles density functional theory and the modern theory of polarization. This study focuses on unidirectional surface PT caused by external EFs at various orientations toward the surface. The preferred PT pathway can change depending on the magnitude and direction of the EF.

Bulky magnesium(ii) and sodium(i) bisphenoxide catalysts for chemoselective transesterification of methyl (meth)acrylates.

Given the industrial importance of (meth)acrylate esters, various groups have devoted considerable effort to investigating their chemoselective transesterification. In 2021, we developed magnesium(ii) and sodium(i) complexes derived from 2,6-di--butyl--cresol (BHT-H) as chemoselective catalysts for the transesterification of methyl acrylate (MA) and methyl methacrylate (MMA), respectively. Based on our results, we report the discovery of magnesium(ii) and sodium(i) salts derived from 6,6'-(propane-2,2'-diyl)bis(2,4-di--butylphenol) (PBTP-H), Mg(PBTP) and Na(PBTP), which are 41 and 81 times more effective catalysts than Mg(BHT) and Na(BHT) for the transesterification of MA and MMA, respectively.

Iron/Photosensitizer Hybrid System Enables the Synthesis of Polyaryl-Substituted Azafluoranthenes.

Photosensitization of organometallics is a privileged strategy that enables challenging transformations in transition-metal catalysis. However, the usefulness of such photocatalyst-induced energy transfer has remained opaque in iron-catalyzed reactions despite the intriguing prospects of iron catalysis in synthetic chemistry. Herein, we demonstrate the use of iron/photosensitizer-cocatalyzed cycloaddition to synthesize polyarylpyridines and azafluoranthenes, which have been scarcely accessible using the established iron-catalyzed protocols.

Asymmetric Dehydrative Cyclization of Allyl Alcohol to Cyclic Ether Using Chiral Brønsted Acid/CpRu(II) Hybrid Catalysts: A DFT Study of the Origin of Enantioselectivity.

To elucidate the reaction mechanism and the origin of the enantioselectivity of the asymmetric dehydrative cyclization of allyl alcohol to cyclic ether catalyzed by a Cp-ruthenium complex and a chiral pyridinecarboxylic acid, ()-X-Naph-PyCOOH, density functional theory (DFT) calculations were performed. According to the DFT calculations, the rate-determining step is the dehydrative σ-allyl formation step with Δ = 18.1 kcal mol at 80 °C.

Exploration of Chemical Space for Designing Functional Molecules Accounting for Geometric Stability.

The design of functional molecules is regarded as searching for molecules with desired functionalities in chemical space populated by candidate molecules. Considering the geometric stability of molecules during the search process is crucial for designing realistic molecules. Here, we propose a method for designing functional molecules by exploring chemical space while explicitly accounting for geometric stability based on computational quantum alchemy.

Mechanism of BPh -Catalyzed N-Methylation of Amines with CO and Phenylsilane: Cooperative Activation of Hydrosilane.

BPh catalyzes the N-methylation of secondary amines and the C-methylenation (methylene-bridge formation between aromatic rings) of N,N-dimethylanilines or 1-methylindoles in the presence of CO and PhSiH ; these reactions proceed at 30-40 °C under solvent-free conditions. In contrast, B(C F ) shows little or no activity. B NMR spectra suggested the generation of [HBPh ] .

Doubly linked chiral phenanthrene oligomers for homogeneously π-extended helicenes with large effective conjugation length.

Helically twisted conductive nanocarbon materials are applicable to optoelectronic and electromagnetic molecular devices working on the nanometer scale. Herein, we report the synthesis of per-peri-perbenzo[5]- and [9]helicenes in addition to previously reported π-extended [7]helicene. The homogeneously π-extended helicenes can be regarded as helically fused oligo-phenanthrenes.

C-H Bond Activation Mechanism by a Pd(II)-(μ-O)-Au(0) Structure Unique to Heterogeneous Catalysts.

We focused on identifying a catalytic active site structure at the atomic level and elucidating the mechanism at the elementary reaction level of liquid-phase organic reactions with a heterogeneous catalyst. In this study, we experimentally and computationally investigated efficient C-H bond activation for the selective aerobic α,β-dehydrogenation of saturated ketones by using a Pd-Au bimetallic nanoparticle catalyst supported on CeO (Pd/Au/CeO) as a case study. Detailed characterization of the catalyst with various observation methods revealed that bimetallic nanoparticles formed on the CeO support with an average size of about 2.

Photoinduced Copper-Catalyzed Asymmetric Acylation of Allylic Phosphates with Acylsilanes.

We report a visible-light-induced copper-catalyzed highly enantioselective umpolung allylic acylation reaction with acylsilanes as acyl anion equivalents. Triplet-quenching experiments and DFT calculations supported our reaction design, which is based on copper-to-acyl metal-to-ligand charge transfer (MLCT) photoexcitation that generates a charge-separated triplet state as a highly reactive intermediate. According to the calculations, the allylic phosphate substrate in the excited state undergoes novel molecular activation into an allylic radical weakly bound to the copper complex.

A boron-transfer mechanism mediating the thermally induced revival of frustrated carbene-borane pairs from their shelf-stable adducts.

Chemists have designed strategies that trigger the conformational isomerization of molecules in response to external stimuli, which can be further applied to regulate the complexation between Lewis acids and bases. We have recently developed a system in which frustrated carbene-borane pairs are revived from shelf-stable but external-stimuli-responsive carbene-borane adducts comprised of N-phosphine-oxide-substituted imidazolylidenes (PoxIms) and triarylboranes. Herein, we report the detailed mechanism on this revival process.

Impact of tensile and compressive forces on the hydrolysis of cellulose and chitin.

Mechanochemistry enables unique reaction pathways in comparison to conventional thermal reactions. Notably, it can achieve selective hydrolysis of cellulose and chitin, a set of abundant and recalcitrant biomass, by solvent-free ball-milling in the presence of acid catalysts. Although the merits of mechanochemistry for this reaction are known, the reaction mechanism is still unclear.