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Despite the importance of rhodium complexes in catalysis, and the favorable 100% natural abundance of the spin-1/2 103Rh nucleus, there are few reports of 103Rh nuclear magnetic resonance (NMR) parameters in the literature. In part, this is the consequence of the very low gyromagnetic ratio of 103Rh and its dismal NMR sensitivity. In a previous paper [Harbor-Collins et al., J. Chem. Phys. 159, 104 307 (2023)], we demonstrated an NMR methodology for 1H-enhanced 103Rh NMR and demonstrated an application to the 103Rh NMR of the dirhodium formate paddlewheel complex. In this paper, we employ selective 18O labeling to break the magnetic equivalence of the 103Rh spin pair of dirhodium formate. This allows the estimation of the 103Rh–103Rh spin–spin coupling and provides access to the 103Rh singlet state. We present the first measurement of a 18O-induced 103Rh secondary isotope shift as well as the first instance of singlet order generated in a 103Rh spin pair. The field-dependence of 103Rh singlet relaxation is measured by field-cycling NMR experiments. [ABSTRACT FROM AUTHOR]

The nuclear magnetic resonance (NMR) spectroscopy of spin-1/2 nuclei with low gyromagnetic ratio is challenging due to the low NMR signal strength. Methodology for the rapid acquisition of 103Rh NMR parameters is demonstrated for the case of the rhodium formate "paddlewheel" complex R h 2 (H C O 2 ) 4 . A scheme is described for enhancing the 103Rh signal strength by polarization transfer from 1H nuclei, which also greatly reduces the interference from ringing artifacts, a common hurdle for the direct observation of low-γ nuclei. The 103Rh relaxation time constants T1 and T2 are measured within 20 min by using 1H-detected experiments. The field dependence of the 103Rh T1 is measured. The high-field relaxation is dominated by the chemical shift anisotropy mechanism. The 103Rh shielding anisotropy is found to be very large: |Δσ| = 9900 ± 540 ppm. This estimate is compared with density functional theory calculations. [ABSTRACT FROM AUTHOR]

We developed a redox-neutral synthesis of isoindoloindolone via intramolecular arylation of 2-(1 H -indole-1-carbonyl)benzoic acids. This protocol facilitates the formation of various substituted isoindoloindolones in yields ranging from 17% to 80%. Our mechanistic investigations indicate the pivotal role of NaI: the iodide anion promotes the formation of the desired isoindoloindolone, and the sodium cation suppresses the formation of acylated byproducts, thereby enabling the selective formation of isoindoloindolones in acceptable yields. [ABSTRACT FROM AUTHOR]

This study introduces a series of Rh–Pd bimetallic aerogels Rh 75 Pd 25 , Rh 50 Pd 50 , and Rh 25 Pd 75 as efficient electrocatalysts for ethanol electrooxidation, crucial for direct ethanol fuel cell technology. The bimetallic Rh–Pd and monometallic Rh and Pd aerogels were synthesized from RhCl 3 and PdCl 2 as starting materials and sodium borohydride as the reducing agent. A combination of X-ray photoelectron spectroscopy, elemental mapping, and electron microscopy studies of the bimetallic aerogels enable compositional analysis of the materials and provide insight into the porous 3D nanoarchitecture. Importantly, the material performs efficiently as an electrocatalyst on glassy carbon electrodes for the oxidation of ethanol under basic conditions (1.0 M KOH) at onset potentials ranging from −0.59 to −0.64 V (vs. Hg/HgO). Importantly, these materials exhibit high peak current densities of 216 mA/cm2 for the Rh-rich Rh 75 Pd 25 to 536 mA/cm2 for Rh 25 Pd 75 , which are significantly higher than reported peak current densities for other Pd-containing electrocatalysts. The 1H and 13C NMR techniques were used to evaluate products for ethanol electrooxidation, with the results indicating selectivity for acetic acid. This demonstrates an enhanced catalytic activity, selectivity to acetic acid vs. CO 2 , representing a significant step in advancing DEFCs and their broader application in sustainable energy technologies. [Display omitted] • Synthesis different Rh–Pd bimetallic aerogels Rh 75 Pd 25 , Rh 50 Pd 50 , and Rh 25 Pd 75. • Highly efficient electrocatalysts for ethanol electrooxidation. • Significant enhancements in catalytic activity to 536 mA/Cm2. • Bimetallic Rh–Pd aerogels selectively convert ethanol to acetic acid. [ABSTRACT FROM AUTHOR]

Kalmanol, the flagship member of the kalmane diterpene family, possesses a complex and highly oxidized 5/5/8/5 tetracyclic skeleton with nine contiguous stereocenters and exhibits significant analgesic effects and cardiotoxic properties. We have achieved the efficient total synthesis of (+)‐kalmanol in 22 steps with 2.3 % yield. The synthesis featured a Rh‐catalyzed [5+2+1] cycloaddition reaction to construct 5/5/8 tricyclic skeleton, and a meticulously designed sequence of stereoselective oxidations of the 5/5/8/5 tetracyclic skeleton. [ABSTRACT FROM AUTHOR]

Fluorinated molecules are widely used in pharmaceutical and agrochemical industries. Multifluoroalkyl-containing compounds have attracted increasing attention for their unique ability to alter the activity of drugs and bioactive molecules. Herein, we report an efficient Rh(III)-catalyzed, redox-neutral, C–H multifluoroalkenylation of benzamides with multifluoroalkenes, which provides a versatile protocol for accessing a wide range of multifluoroalkenylated arenes. [ABSTRACT FROM AUTHOR]

The catalytic direct hydroarylation of alkynamides is a highly efficient approach for accessing functionalized trisubstituted arylalkenes with amide groups. Herein, we report a rhodium‐catalyzed pyridylation of alkynamides with pyridylboronic acids, producing a variety of primary, secondary, and tertiary enamides with high yields (up to 94 %). This reaction demonstrates broad tolerance towards various alkyl and aryl functional groups, providing convenient access to a diverse array of alkenylpyridine derivatives. To demonstrate potential applications in late‐stage hydropyridylation, we synthesized α,β‐unsaturated ketones, aldehydes, and esters with high yields from the pyridylation product of Weinreb amides. This indirect expansion of the substrate scope enhances the practicality of this strategy. Additionally, the α,β‐unsaturated ketone obtained can be further reduced to yield a chiral alcohol with a 99 % ee, further demonstrating the versatility and potential utility of this approach. [ABSTRACT FROM AUTHOR]

We have developed the Rh‐catalyzed enantioselective [2+2+2] cycloaddition of homopropargyl enamides (tosylamide‐tethered 1,6‐enynes) with alkynes to construct tetrahydroindole skeletons found in natural alkaloids and pharmaceuticals. This cycloaddition proceeds at room temperature in high yields and regio‐ and enantioselectivity with a broad substrate scope. The preparative scale reaction followed by substituent conversion on the nitrogen atom and the diastereoselective [4+2] cycloaddition with singlet O2 affords hexahydroindole‐diols bearing three stereogenic centers and variable substituents on the nitrogen. Mechanistic studies have revealed that the substituents of the enynes change the ratio of intramolecular and intermolecular rhodacycle formation when using terminal alkynes, varying the ee values of the cycloadducts. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Herein, we report rhodium catalyzed N‐arylation via addition of arylboronic acids to electron‐deficient α‐iminoesters which can be prepared in high efficiency by using easily accessible β‐carbonyl esters. The reaction is highly regiospecific to achieve the N‐aryl addition efficiently with up to 99% yield under mild conditions. The corresponding product can be further efficiently converted into indoles and a series of other important building blocks. [ABSTRACT FROM AUTHOR]

A facile synthesis of Pt-Rh 2 O 3 /CN x composite is reported for superior electrocatalytic hydrogen evolution and oxidation reaction (HER/HOR) in base. The HER/HOR performance of Pt-Rh 2 O 3 /CN x is ∼6/3.4 times better than commercial Pt/C. Both the hydrogen and hydroxyl binding energy are equal descriptors for alkaline HER/HOR. The hydrogen spillover from Pt to Rh 2 O 3 enhances the HER/HOR performance. The role of hydroxyl-metal-water species on alkaline HOR was also discussed. [Display omitted] • The Platinum/Rhodium Oxide-Nitrogen-Doped Carbon (Pt/Rh 2 O 3 -CN x) nanocomposite was prepared for bifunctional HER/HOR in base media. • The HOR/HER activities of Pt/Rh 2 O 3 -CN x are ∼ 3.5/6 times higher than commercial Pt/C. • Experimental, theoretical studies suggest H-spillover increases catalytic activity. • HBE and OHBE are responsible for alkaline HER/HOR; a bifunctional mechanism was proposed. • Interfaces, porosity, ECSA, and synergetic interactions also helped for high activity. The poor activity of Pt-based-catalysts for alkaline hydrogen oxidation/evolution reaction (HOR/HER) encourages scientific society to design an effective electrocatalyst to develop alkaline fuel cells/electrolyzers. Herein, platinum/rhodium oxide-nitrogen-doped carbon (Pt/Rh 2 O 3 -CN x) composite is prepared for alkaline HER and HOR inspired by hydrogen spillover. The HER performance of Pt/Rh 2 O 3 -CN x is ∼ 6 times higher than Pt/C. In HOR, Pt/Rh 2 O 3 -CN x possesses an exchange current density of 657.60 mA/mg metal , which is ∼ 3.4 times higher than Pt/C. Hydrogen and hydroxyl binding energy (HBE and OHBE) contribute equally to alkaline HOR/HER. The experimental and theoretical evidence suggests that the enhanced HER and HOR activity of Pt/Rh 2 O 3 -CN x may be due to hydrogen spillover from Pt to Rh 2 O 3. Small work function difference [0.08 eV] of the system suggested hydrogen-spillover is feasible, which has been justified by reaction-free energy calculations. We proposed that the dissociation of hydrogen (H 2) and water (H 2 O) occurs at Pt to form Pt-adsorbed hydrogen species (Pt-H ad). Then, some H ad moves to Rh 2 O 3 through hydrogen spillover and reacts with neighboring H ad or adsorbed hydroxyl species (OH ad) to form H 2 or H 2 O, which enhances the HER and HOR activity, respectively. The role of water-metal-hydroxyl species in the electrical double layer was also demonstrated on alkaline HOR/HER. This work may help to design the hydrogen-spillover-based catalysts for several renewable energy technologies. [ABSTRACT FROM AUTHOR]

This report presents a selective synthetic approach towards borazine from ammonia borane using a dinuclear rhodium olefin homogeneous catalyst. The synthesis and spectroscopic characterization of a dirhodium ammonia borane complex as an intermediate provides insight into a possible mode of activation. [ABSTRACT FROM AUTHOR]

Heteronuclear coordination compounds of d-metals are effective precursors for the production of bimetallic nanoalloys (Plyusnin et al., 2022) [1], which, in turn, are widely used in catalysis. Catalysts based on Rh and Cu, as well as Rh and Zn, are highly active in the process of steam reforming of hydrocarbons. Double oxalates of Rh with Cu and Rh with Zn with the general formula [(C 2 O 4)(H 2 O) 2 Rh−(μ-C 2 O 4)−M(H 2 O) 2 −(μ-C 2 O 4)–Rh(H 2 O) 2 (C 2 O 4)]·6H 2 O (M = Cu, Zn) are synthesized and structurally characterized. According to thermogravimetric analysis, the complexes completely decompose in He and H 2 atmospheres already at 300 °C with the formation of the corresponding nanoalloys in the Cu–Rh and Zn–Rh systems. Calcination in an O 2 atmosphere leads to the formation of a mixed oxide with a spinel structure. The Cu–Rh/Ce 0.75 Zr 0.25 O 2 and Zn–Rh/Ce 0.75 Zr 0.25 O 2 catalysts were prepared by impregnation by moisture capacity on a porous support followed by calcination in a hydrogen atmosphere. The obtained catalysts were tested in propane steam reforming for hydrogen production at 300–480 °C and WHSV = 10 000–40 000 cm3 h−1∙g cat −1. At these conditions the Cu–Rh/Ce 0.75 Zr 0.25 O 2 and Zn–Rh/Ce 0.75 Zr 0.25 O 2 catalysts demonstrated high selectivity for hydrogen (more than 70 %) compared to the monometallic catalyst Rh/Ce 0.75 Zr 0.25 O 2 (less than 60%). Bimetallic catalysts make it possible to increase hydrogen productivity by reducing the reaction rate of methanation of carbon oxides, which is achieved due to the presence of Cu and Zn in the catalyst structure. • New coordination compounds of rhodium with copper and zinc have been synthesized. • Bimetallic systems were obtained in a reducing and inert atmosphere. • Bimetallic Cu–Rh/CZ catalysts exhibit high hydrogen selectivity in the propane steam reforming reaction. • Bimetallic Cu–Rh/CZ and Zn–Rh/CZ catalysts reduce the rate of methanation reaction during propane steam reforming. [ABSTRACT FROM AUTHOR]

Decomposition of aryl and unsubstituted diazo ester into Rh(II)‐carbenes by the [(IMes)Rh2(OAc)4] complex is shown to be slower than with Rh2(OAc)4. Diazo esters substituted by a second electron‐withdrawing group do not suffer nitrogen extrusion when exposed for several hours to this (NHC)Rh(II) complex at room temperature. This chemoselective decomposition of diazo esters depending on their substituent (Ar, H, EWG) can furthermore be achieved on a mixture of substrates. The catalytic activity of [(IMes)Rh2(OAc)4] towards electron‐poor diazo compounds is also restored by heating to reflux in chloroform, or after decomplexation of the NHC by addition of GaCl3. The [(IMes)Rh2(OAc)4] complex was then used to induce a fully selective reaction cascade from a mixture of two diazo esters. First, a donor/acceptor diazo compound was decomposed selectively at room temperature to give an intermolecular O−H insertion product without any decomposition of the electron poor diazo compound. Addition of GaGl3 then triggered nitrogen extrusion from the diazo malonate to give a 1,5‐C−H insertion product. This transformation, where decomposition of diazo compounds catalyzed by Rh(II) complexes can be externally controlled, represents the first example of assisted tandem catalysis with two metal carbene precursors. [ABSTRACT FROM AUTHOR]

Rhodium complexes in the −I and 0 oxidation states are of great potential interest in catalytic applications. In contrast to their rhodium +I congeners, however, the structural and electronic parameters governing their access and stability are far less understood. Herein, we investigate the two‐electron reduction of a parameterized series of bis(diphosphine) Rh complexes [Rh(dxpy)2]NTf2 (x=P‐substituent, y=alkanediyl bridging P atoms). Through (electro)reductions from the RhI parents, Rh−Id10‐complexes were obtained and characterized spectroscopically, including 103Rh NMR data. The reductive steps convolute with structural rearrangements from square planar to tetrahedral coordination. We found that the extent of these reorganisations defines whether the first E0(RhI/0) and second E0(Rh0/−I) reduction potentials are normally ordered, leading to monoelectronic stepwise transitions, or inverted, giving bielectronic events. Reductionist approaches based on Hammett parameters or the P−Rh‐P bite angles provide only partial correlations with the redox potentials. However, we identified the C−O stretch of analogue diphosphine complexes as an expedient computational parameter that enables these correlations through both electronic and geometric features, even in a predictive manner. Gaining control over two‐electron reduction behaviors through rationalized ligand effects has potential impact beyond Rh complexes, for molecular and enzymatic metal sites commonly exhibiting bielectronic transitions. [ABSTRACT FROM AUTHOR]

Supported metal single atom catalysis is a dynamic research area in catalysis science combining the advantages of homogeneous and heterogeneous catalysis. Understanding the interactions between metal single atoms and the support constitutes a challenge facing the development of such catalysts, since these interactions are essential in optimizing the catalytic performance. For conventional carbon supports, two types of surfaces can contribute to single atom stabilization: the basal planes and the prismatic surface; both of which can be decorated by defects and surface oxygen groups. To date, most studies on carbon‐supported single atom catalysts focused on nitrogen‐doped carbons, which, unlike classic carbon materials, have a fairly well‐defined chemical environment. Herein we report the synthesis, characterization and modeling of rhodium single atom catalysts supported on carbon materials presenting distinct concentrations of surface oxygen groups and basal/prismatic surface area. The influence of these parameters on the speciation of the Rh species, their coordination and ultimately on their catalytic performance in hydrogenation and hydroformylation reactions is analyzed. The results obtained show that catalysis itself is an interesting tool for the fine characterization of these materials, for which the detection of small quantities of metal clusters remains a challenge, even when combining several cutting‐edge analytical methods. [ABSTRACT FROM AUTHOR]

The present study provided an efficient synthesis pathway to the azepino[5,4,3‐cd]indoles using N‐sulfonyl‐1,2,3‐triazoles and 4‐vinylindoles through a cascade carbene insertion and intramolecular aza‐Michael addition. This method is distinguished by mild reaction conditions, straightforward operational steps, accessible starting materials and broad substrate compatibility. Furthermore, the versatility of this reaction with various Michael acceptors significantly broadens the scope of potential substrates. The ability to further transform the resulting multifunctional products underscores the promising applications of this approach in indole nitrogen heterocyclic synthesis. [ABSTRACT FROM AUTHOR]

This article traces the development of synthetic routes toward 1-indanones containing a β-quaternary carbon center. The recent advancement in the regio- and chemoselective formal (4+1) carbocyclization of chalcones with internal alkynes via rhodium(III) catalysis for the synthesis of 1-indanones is highlighted. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: The rhodium‐catalyzed C—H bond activation and cyclization of 3‐oxopent‐4‐enenitriles with alkynes proceed efficiently. Various 2H‐pyrans with multiple substituents are achieved in good yields through regioselective formation of C—O and C—C bonds. Transformations involving hydroxy‐alkynoates resulted in products with a furo[3,4‐b]pyran skeleton via further intramolecular ester exchange processes. Different from the traditional "1‐oxatrienes pathway", this method for the synthesis of useful 2H‐pyrans possesses certain highlights in terms of readily available substrates, stable and easily derivatized products, gentle and convenient operation process, and step and atom economy. [ABSTRACT FROM AUTHOR]

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Carbodicarbenes are strong C‐donor ligands, which have found numerous applications in organometallic and main group element chemistry. Herein, we report a structurally distinct carbodicarbene ligand, which is formed by dinitrogenative coupling of a Fischer carbene complex with an N‐heterocyclic diazoolefin. The resulting carbonyl complex serves as a stable source for the mixed Arduengo‐Fischer carbodicarbene ligand. Facile ligand transfer reactions were demonstrated to occur with gold(I), copper(I), palladium(II), and rhodium(I) complexes. [ABSTRACT FROM AUTHOR]

We report herein of a novel, enantioselective and rhodium‐ catalyzed cyclisation of allenyl alcohols towards chiral α‐vinylic, cyclic ethers employing a rhodium/(R,R)‐Me‐ferrocelane catalyst. The corresponding chiral cyclic products were obtained in general high yields and enantioselectivities. The synthetic value of our obtained products was further exemplified by transformations of the allylic ether function. Furthermore, applying our newly developed method in our previously reported route towards the total synthesis of (R,R,R)‐α‐tocopherol, we accomplished a significantly improved 2nd generation synthesis of the chromane building providing a total number of 13 steps and an overall total yield of 27 %. [ABSTRACT FROM AUTHOR]

Covalent immobilization of chiral dienes in mesoporous solids for asymmetric heterogeneous catalysis is highly attractive. In order to study confinement effects in bimolecular vs monomolecular reactions, a series of pseudo‐C2‐symmetrical tetrahydropentalenes was synthesized and immobilized via click reaction on different mesoporous solids (silica, carbon, covalent organic frameworks) and compared with homogeneous conditions. Two types of Rh‐catalyzed reactions were studied: (a) bimolecular nucleophilic 1,2‐additions of phenylboroxine to N‐tosylimine and (b) monomolecular isomerization of isoxazole to 2H‐azirne. Polar support materials performed better than non‐polar ones. Under confinement, bimolecular reactions showed decreased yields, whereas yields in monomolecular reactions were only little affected. Regarding enantioselectivity the opposite trend was observed, i. e. effective enantiocontrol for bimolecular reactions but only little control for monomolecular reactions was found. [ABSTRACT FROM AUTHOR]

Molecules with chiral boron atoms have been scarcely studied due to limited synthetic access. Herein, we report a new method for their synthesis via asymmetric insertion of arydiazoacetates into the B–H bonds of prochiral carbene–boranes NHC–BH2R. The reaction is catalyzed by the rhodium(I) complex with the chiral diene ligand tBu2-TFB, which can be conveniently prepared by diastereoselective coordination of the racemic diene with (S-Salox)Rh(CO)2. The target boranes were typically obtained in 75–90% yields with 90–95% ee. [ABSTRACT FROM AUTHOR]

Within the series of the equiatomic REAlRh compounds, the representatives with RE = Y, La–Nd, Gd, Ho, Tm and Yb have been synthesized. The members with RE = Sm, Tb, Dy, Er and Lu, however, had not yet been reported. They have now been synthesized and structurally as well as magnetically and NMR-spectroscopically characterized. All members crystallize isostructurally in the orthorhombic TiNiSi type, similar to most of the known analogues. The evolution of their unit cell volumes exhibits the expected decrease due to the lanthanide contraction. While LuAlRh shows Pauli-paramagnetic behavior, SmAlRh, TbAlRh, DyAlRh, ErAlRh, and TmAlRh exhibit antiferromagnetic ground states with Néel temperatures between TN = 45 and 4 K. 27Al MAS-NMR investigations have been conducted on YAlRh and LuAlRh. The results of quantum-chemical calculations support the conclusions drawn from the NMR-spectroscopic study and give information on the charge distribution in these intermetallic aluminum metallides. [ABSTRACT FROM AUTHOR]

Cationic‐shell core‐crosslinked micelles (CCM−C) with rhodium nanoparticles (RhNPs) anchored to core‐linked triphenylphosphine oxide (TPPO) ligands were synthesized by a facile one‐pot approach by the reduction of [Rh(COD)(μ‐Cl)]2/toluene in the presence of an aqueous TPPO@CCM−C latex. The resulting RhNP‐TPPO@CCM−C latex showed to be performant for the aqueous biphasic hydrogenation of styrene with an average corrected turnover frequency (cTOF) up to 23600 h−1 based on the RhNP surface atoms. The catalyst system also proved reusable in multiple catalytic runs without any visible RhNP loss during the recycling process as well as applicable to the hydrogenation of other selected alkenes, alkynes and carbonyl substrates (average cTOF of 1000–3200 h−1), thus demonstrating a high versatility. [ABSTRACT FROM AUTHOR]

Isoindolinones are vital heterocyclic compounds in medicinal chemistry, notable for their diverse bioactivities. Significant attention has been devoted to their preparation; however, existing methods are unsuitable for constructing unsubstituted 3‐methyleneisoindolin‐1‐ones. Herein, we present a rhodium(III)‐catalyzed method for synthesizing unsubstituted 3‐methyleneisoindolin‐1‐ones via C−H/N−H activation and annulation of N‐methoxybenzamides with potassium (ethenyl)trifluoroborate. This approach offers mild reaction conditions, high regioselectivity, and efficient yields. Interestingly, sterically demanding or heterocyclic N‐methoxyaromaticamides resulted in the formation of 2‐vinyl(hetero)aromatic amides instead of 3‐methyleneisoindolin‐1‐ones. Mechanistic insights suggest a rhodacycle intermediate pathway, highlighting the method's potential for developing new bioactive isoindolinone derivatives. [ABSTRACT FROM AUTHOR]

Development of chiral indenyl ligands for asymmetric C−H activation is a longstanding challenge, and extremely few successes have been achieved. In this paper, we describe a class of readily accessible, facilely tunable and user‐friendly chiral indenyl ligands featuring a [2.2]benzoindenophane skeleton via a divergent synthesis strategy. The corresponding chiral indenyl rhodium catalysts were successfully applied in the asymmetric C−H activation reaction of O‐Boc hydroxybenzamide with alkenes to give various chiral dihydroisoquinolone products (up to 97 % yield, up to 98 % ee). Moreover, the asymmetric C−H activation reaction of carboxylic acids with alkynes was also successfully accomplished, providing a range of axially chiral isocoumarins (up to 99 % yield, up to 94 % ee). Notably, this represents the first example of enantioselective transition metal catalyzed C(sp2)−H activation/oxidative coupling of benzoic acids with internal alkynes to construct isocoumarins. Given many attractive features of this class of indenyl ligands, such as convenient synthesis, high tunability and exclusive face‐selectivity of coordination, its applications in more catalytic asymmetric C−H activation and in other asymmetric catalysis are foreseen. [ABSTRACT FROM AUTHOR]

A novel method was developed for the determination of ultra-trace rhodium (Rh) in geological samples. Using Sb2O3 as fire assay collector, Rh in 10 to 20 g was pre-concentrated in 50 mg Sb granules. After the granules were microwave digested in aqua regia (40%, v/v), 103Rh was determined by high radio-frequency (RF) power cold plasma and kinetic energy discrimination collision cell-inductively coupled plasma-mass spectrometry (KED-ICP-MS). Four methods to eliminate the mass spectral interferences of 206Pb2+ and 40Ar63Cu to 103Rh including standard mode (STD-ICP-MS) hyphenated with equivalent concentration correction of 206Pb2+ and 40Ar63Cu, KED-ICP-MS hyphenated with equivalent concentration correction of 206Pb2+, high RF power cold plasma ICP-MS hyphenated with equivalent concentration correction of 40Ar63Cu, and high RF power cold plasma hyphenated with KED-ICP-MS were compared. The first three methods required equivalent concentration correction so the Pb and Cu content in the sample solutions were determined in advance and subtracted. On the contrary, the interferences were eliminated by high RF power cold plasma hyphenated with KED-ICP-MS. The RF power of cold plasma was studied. Moreover, the He collision gas, nebulizer flow and sampling depth were optimized. Under the optimal conditions, Rh had a linear relationship from 0.001 to 10 ng mL−1 with a correlation coefficient of 0.9999. The detection limit was 0.012 ng g−1. The method was applied to analysis of various matrix certified reference materials (CRMs) and the measured results were in good agreement with the certified values. [ABSTRACT FROM AUTHOR]

One of the main causes of atmospheric pollution comes from mobile sources that emit noxious gases from internal combustion engines. For the suppression of toxic exhaust gases, a catalytic converter is used as an anti-pollution device, because it catalyzes or accelerates the degradation of emissions making them less harmful. In the catalytic converter, platinum (Pt), palladium (Pd) and rhodium (Rh) catalysts are normally used for their excellent performances. However, these metals are expensive, rare, and scarce in the earth's crust. These precious metals thus emphasized the importance of developing efficient recycling practices. For the recycling of these precious metals, a very fast, easy, economical, environmentally friendly and high-safety electric pulse discharge method was used to separate the Pd and Rh from the spent metal-honeycomb (MH) catalytic converter consisting of p as the catalyst carrier. To standardize the precious metals recycling process and attain the highest level of separation of Pd and Rh, electric pulse shots ranging from 120-240 and standoff distances (gap width between the positive electrode and the sample surface) ranging from 5-10mm were applied. During this process, an electrical explosion occurred within the honeycomb structures through the electric shock. After the electrical explosion, the particles are collected, then sieved and physical characterizations are performed. Scanning electron microscope (SEM) and energy dispersive spectroscopy (EDX) analyses revealed that the most separated particles are highly pure, and dispersed homogeneously without destroying particle structures. In this article, we first report about 87.91% of Pd and 90.77% of Rh are separated from each catalytic converter using the electric pulse discharge method that can overcome challenges and achieve ambitious recycling targets in the recycling industry. The effects of the discharge energies and the shock energy determined by varying electric pulse shots and standoff distance, respectively, are discussed. These findings provide insight into the recovery of precious metals for electric pulse discharge and play a role in developing a very effective recycling method not only for the catalytic converter but also for other devices. [ABSTRACT FROM AUTHOR]

The pressure–volume equations of state of palladium and rhodium statically compressed in neon are presented. Vinet fits give parameters for palladium: V 0 = 58.678 (73) Å 3 , B 0 = 189.3 (30) GPa, B 0 ′ = 5.473 (63) , and rhodium: V 0 = 55.062 (63) Å 3 , B 0 = 241.3 (65) GPa, B 0 ′ = 5.34 (24). Both metals are observed to react with hydrocarbons under pressure to form hydrides. Existing equations of state are discussed with regard to potential inadvertent hydrogen contamination as a source for discrepancies and anomalous fitted parameters. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: The first asymmetric hydrogenation of acyclic tetrasubstituted α,β‐unsaturated amides has been achieved by using Rh/DuanPhos complex as a catalyst, delivering chiral β‐amino amides with two contiguous chiral centers in excellent yields and high enantioselectivities (up to 99% yield, 96% ee), which provides efficient and concise access to valuable β‐amino amide derivatives. The gram‐scale reaction and efficient transformation of β‐amino amide to β‐amino acid and β‐amino cyanide demonstrated the utility of this methodology. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: The first asymmetric hydrogenation of acyclic tetrasubstituted α,β‐unsaturated amides has been achieved by using Rh/DuanPhos complex as a catalyst, delivering chiral β‐amino amides with two contiguous chiral centers in excellent yields and high enantioselectivities (up to 99% yield, 96% ee), which provides efficient and concise access to valuable β‐amino amide derivatives. The gram‐scale reaction and efficient transformation of β‐amino amide to β‐amino acid and β‐amino cyanide demonstrated the utility of this methodology. [ABSTRACT FROM AUTHOR]

Introduction. The development of methodological issues of optimizing the activities of mining and metallurgical companies and the sale of platinum group metals are highly relevant in the current market conditions due to sanctions restrictions and the severance of international economic ties. Theoretical analysis. The concept of an optimization model is formulated, the main goals for the sales unit of a mining and metallurgical company are determined, a balanced approach to monthly planning is justified, which involves dividing the sales volume into two parts: under long-term contracts and on the spot market, and the stages of constructing an optimization sales model are developed. Empirical analysis. An optimization model is presented for calculating sales volumes of platinum, palladium and rhodium within two months to obtain maximum operating profit. The model is based on regression modeling of prices for platinum group metals, a cost model built on open data from a Russian mining and metallurgical company. Results. Approbation of the methodology made it possible to justify the sales volumes of platinum group metals in two forecast periods depending on the price environment, which provide the opportunity to increase the total profit of the company under given restrictions.

1,2,3‐Thiadiazoles exhibit versatile reactivity due to their ability to undergo ring cleavage, forming α‐diazothione species through a Dimroth‐type equilibrium. Denitrogenation of the α‐diazothione, induced by high temperature, irradiation, or strong bases, allows generation of a wide range of reactive intermediates. Since 2016, the transition‐metal‐catalyzed denitrogenative transannulation of 1,2,3‐thiadiazoles has garnered significant attention as a promising approach to constructing diverse heterocyclic scaffolds. This review focuses on the denitrogenative reactions of 1,2,3‐thiadiazoles, particularly highlighting the novel rhodium‐catalyzed denitrogenative transannulation transformations along with their mechanisms. [ABSTRACT FROM AUTHOR]

Herein, we report the use of a molecular-defined rhodium(II) coordination polymer (Rh-CP) as a heterogeneous, recyclable catalyst in carbene transfer reactions. We showcase the application of this heterogeneous catalyst in a range of carbene transfer reactions and conclude with the functionalization of natural products and drug molecules. [ABSTRACT FROM AUTHOR]

The κ2‐(P,N)−phosphine ligand precursor NH(CH2CH2PCy2)2 can be used for the synthesis of the rhodium(I) complex [Rh(CO){ĸ3‐(P,N,P)−Cy2PC2H4NHC2H4PCy2}][Cl] (1). The deprotonated complex [Rh(CO){ĸ3‐(P,N,P)−Cy2PC2H4NC2H4PCy2}] (2) shows a cooperative reactivity of the PNP ligand in the activation reaction of SO2F2 to yield the rhodium fluorido complex trans‐[Rh(F)(CO){ĸ2‐(P,P)−Cy2PC2H4N(SO2F)C2H4PCy2}]2 (3) by S−F bond cleavage. It is remarkable that no reaction was observed when 3 was treated with hydrogen sources e. g. dihydrogen, organosilicon compounds such as triethylsilane or TMS−CF3 and different fluorine sources such as SF4 or Selectfluor®. However, the treatment of complex 3 with XeF2 in the presence of CsF resulted in the formation of the unique fluorido rhodium(III) complex cis,trans‐[Rh(F)3(CO){ĸ2‐(P,P)−Cy2PC2H4N(SO2F)C2H4PCy2}]2 (4). In the presence of pyridine(HF)X or BF3 the fluorido complex 3 converted into the dicationic complexes [Rh(CO){ĸ2‐(P,P)−Cy2PC2H4N(SO2F)C2H4PCy2}]2[XF]2, X=HF (5) or BF3 (6), respectively. [ABSTRACT FROM AUTHOR]

The decrease in noble metal content presents an efficient approach to attain commercial, effective, and durable electrocatalysts for the hydrogen evolution reaction (HER) at a low fabrication cost. Nonetheless, achieving a proper balance between bimetallic loading ratios and HER performance remains challenging. In this study, a simple and environmentally friendly sonochemical method is employed to successfully synthesize bimetallic palladium–rhodium nanoparticles (Pd‐Rh) with varying ratios, confined within molybdenum disulfide (MoS2) nanosheets. Bimetallic Pd‐Rh/MoS2 composite with different ratios of Pd:Rh is synthesized by adjusting the feed ratio of Pd and Rh precursors (1:4, 1:1, and 4:1). The HER electrocatalytic activity of the bimetallic Pd1‐Rh1/MoS2 composite exhibits the lowest overpotential and a superior Tafel slope, closely rivaling the electrocatalytic activity of the commercial 20 wt% Pt/C. Furthermore, the bimetallic Pd1‐Rh1/MoS2 composite exhibits remarkable stability and durability, with almost negligible performance decay after 2000 cycles. These outstanding HER electrocatalytic properties of the bimetallic composite result from a higher number of active sites, a significantly larger electrochemically active surface area, reduced charge‐transfer resistance, and a larger double‐layer capacitance. These factors collectively facilitate faster adsorption and desorption of hydron on the surface of electrocatalyst. [ABSTRACT FROM AUTHOR]

Rh(III) and Ru(II) complexes, [RhCl2(κ4‐N2N'P‐L)][SbF6] (1) and [RuCl2(κ4‐N2N'P‐L)] (2), were synthesised using the tetradentate ligand L (L=N,N‐bis[(pyridin‐2‐yl)methyl]‐[2‐(diphenylphosphino)phenyl]methanamine). In each case only one diastereomer is detected, featuring cis‐disposed pyridine groups. The chloride ligand trans to pyridine can be selectively abstracted by AgSbF6, with the ruthenium complex (2) reacting more readily at room temperature compared to the rhodium complex (1) which requires elevated temperatures. Rhodium complexes avoid the second chloride abstraction, whereas ruthenium complexes can form the chiral bisacetonitrile complex [Ru(κ4‐N2N'P‐L)(NCMe)2][SbF6]2 (5) upon corresponding treatment with AgSbF6. The complex [RhCl2(κ4‐N2N'P‐L)][SbF6] (1) has also been used to synthesise polymetallic species, such as the tetrametallic complex [{RhCl2(κ4‐N2N'P‐L)}2(μ‐Ag)2][SbF6]4 (6) which was formed with complete diastereoselectivity and chiral molecular self‐recognition. In addition, a stable bimetallic mixed‐valence complex [{Rh(κ4‐N2N'P‐L)}{Rh(COD)}(μ‐Cl)2][SbF6]2 (7) (COD=cyclooctadiene) was synthesised. These results highlight the significant differences in chloride lability between Rh3+ and Ru2+ complexes and demonstrate the potential for complexes to act as catalyst precursors and ligands in further chemistry applications. [ABSTRACT FROM AUTHOR]

We stand fully behind our earlier suggestion [Raymond & Girolami (2023). Acta Cryst. C79, 445–455] that the claim by Fish and co‐workers [Chen et al. (1995). J. Am. Chem. Soc.117, 9097–9098; Smith et al. (2014). Organometallics, 33, 2389–2404] of a linear two‐coordinate rhodium(I) species is incorrect, and that the putative rhodium atom is in fact silver. [ABSTRACT FROM AUTHOR]

Hydroformylation of olefins with CO and H2 is an attractive approach to synthesize value-added aldehydes. Numerous efforts have been dedicated to the development of novel and efficient catalyst systems, given the high demand for aldehydes. By immobilizing complexes on the surface of heteroatom-containing porous organic polymers have garnered renewed attention. In this paper, a series of porous organic polymer-supported rhodium catalysts were prepared, of which the results demonstrated that the Rh/PTBA-TTA catalyst with abundant nitrogen and phosphorus exhibited excellent activity (100% conversion) and high linear aldehyde selectivity (74%) for the heterogeneous catalytic hydroformylation reaction of 1-octene. The investigations of catalyst dosage, reaction temperature and partial pressure ratio were conducted. In addition, Rh/PTBA-TTA catalyst displayed broad substrate scope and recyclability. The structures of the catalysts were thoroughly characterized by mean of a spectrum of characterization techniques including FT-IR, XPS, solid-state MAS NMR, SEM and TEM. The data indicate that the presence of highly dispersed Rh active species might be on the Rh/PTBA-TTA catalyst. Moreover, the hot filtration test further confirmed the heterogeneity of the reaction, exhibiting great potential for the industrial applications. A series of nitrogen and phosphorus-containing porous organic polymer-supported Rh catalysts are demonstrated to be highly effective in the hydroformylation of various olefins. [ABSTRACT FROM AUTHOR]

The mechanism of higher alcohol synthesis (HAS) from syngas on a stepped Rhodium surface was explored using first principles calculations based on density functional theory. Results showed that the activation of CO proceeds most energetically feasible via a sequential hydrogenation towards CH2OH, followed by the C–OH bond cleavage yielding CHx species. Because the initial CO hydrogenation step is highly activated, the cascade of elementary steps toward methane formation is highly favored. The formation of C2 oxygenates toward ethanol production is kinetically favored by CO insertion to CH2, or alternatively, by a lower activation barrier CHO insertion to CH3. On the other hand, the C3 species is formed more preferably by CO rather than CHO insertion to a CH3CH2 fragment, indicating the effect of a more extended carbon structure on the reaction mechanism. The overall reaction mechanism for HAS points to a cycle of CO insertion, hydrogenation, and OH elimination steps. [ABSTRACT FROM AUTHOR]

A Rh‐catalyzed asymmetric hydroboration of dialkyl ketone‐derived silyl enol ethers with HBpin has been developed using a commercially available catalyst and ligand ([RhCl (cod)]2 and MeO‐BIBOP). A variety of silyl enol ethers undergo this asymmetric transformation, providing the corresponding products with high enantioselectivity (up to 97 : 3 % er). In addition, the utility of this protocol is demonstrated by the versatile transformation of chiral borylether products to a range of valuable derivatives. [ABSTRACT FROM AUTHOR]

The catalytic access of silicon‐stereogenic organosilanes remains a big challenge, and largely depends on the desymmetrization of the symmetric precursors with two identical substitutes attached to silicon atom. Here we report the construction of silicon‐stereogenic organosilanes via catalytic kinetic resolution of racemic monohydrosilanes with good to excellent selectivity factors. Both Si‐stereogenic dihydrobenzosiloles and Si‐stereogenic monohydrosilanes could be efficiently accessed in one single operation via Rh‐catalyzed enantioselective intramolecular hydrosilylation, employing (R,R)‐Et‐DuPhos as the optimal ligand. This catalytic protocol features mild conditions, a low catalyst loading (0.1 mol % [Rh(cod)Cl]2), high stereoinduction (S factor up to 152), and excellent scalability. Moreover, further derivatizations led to the efficient synthesis of uncommon middle‐size (7‐ and 8‐membered) Si‐stereogenic silacycles. Preliminary mechanistic study indicates this reaction might undergo a modified Chalk–Harrod mechanism. [ABSTRACT FROM AUTHOR]

This article discusses a new method for synthesizing π-conjugated polymers using a ruthenium-catalyzed C-H arylation polymerization. The method involves using visible light irradiation at room temperature, resulting in high yields and high molecular weights of the polymers. The article also explores the use of photochemistry and C-H activation in polymer synthesis, highlighting the advantages of using light energy for mild reactions with high chemoselectivity and functional group tolerance. The document presents a study on the ruthenium-catalyzed polymerization of phenyloxazolines, investigating reaction conditions, reactivity of different arylbromides, and the synthesis of terpolymers. The research demonstrates the potential of ruthenium-catalyzed polymerization for various applications in polymer chemistry. [Extracted from the article]

This article discusses the synthesis of substituted ß-homoprolines using rhodium catalysis. ß-Homoproline is a variant of ¿-proline and is found in natural products and pharmaceuticals. The article describes the development of a new method for synthesizing ß-homoprolines, which involves the cyclization of isoxazolidin-5-ones using a rhodium catalyst. The authors demonstrate the scope and limitations of this method and discuss the downstream transformations that can be performed on the resulting ß-homoprolines. Overall, this research provides valuable insights into the synthesis and potential applications of ß-homoprolines. [Extracted from the article]

This article provides a comprehensive report on the rhodium(III)-catalyzed C–H activation in indole from 2017 to 2022. The direct functionalization of C–H bonds offers a more sustainable and economically sensible route in organic synthesis, reducing the production of hazardous waste. Rhodium has been widely used as a catalyst for C–H functionalization due to its excellent functional group compatibility, versatility, reactivity, and selectivity. The article focuses on the utilization of Rh(III) catalyst for C–H activation of the indole moiety, which is a structurally important building block in natural products and pharmaceutical treatments. Various methods for directed C–H functionalization of indoles, such as C2 activation, alkylation, hydroarylation, and dual C–H activation reactions, are discussed. The text also discusses various methods for the synthesis of carbazole derivatives, benzo[e]indoles, and selective functionalization of indoles through C–H activation. While progress has been made in this area, there are still challenges to overcome, such as the need for harsh reaction conditions and stoichiometric metal oxidants. Continued research in this field is expected to improve reaction conditions and increase overall efficiency. [Extracted from the article]

A carbon‐rich molecule is synthesized, which mainly contains conjugated sp2 and sp hybridized carbon centers. Alkenyl and alkynyl binding sites are arranged such that this compound serves as ligand to a binuclear metal unit with a RhI─RhI bond. Furthermore, CH units are placed in proximity to the metal centers. The dicationic complex [Rh2(bipy)2{Ph2Ptrop(C≡CCy)2}]2+(OTf−)2 allows to study possible responses of the carbon‐framework to redox reactions as well as deprotonation reactions. All products are, whenever possible, characterized by X‐ray diffraction (XRD) methods, NMR and EPR spectroscopy as well as electrochemical methods. It is shown that the carbon skeleton of the ligand framework undergoes C─C bond rearrangement reactions of remarkable diversity. In combination with DFT (density functional theory) studies, these results allow to gain insight into the electronic structure changes caused by metal sites in a carbon‐rich environment, which may be of relevance for the properties of metal particles on carbon support materials when they are exposed to hydrogen, electrons, or protons. [ABSTRACT FROM AUTHOR]

An enantioselective Si−H insertion between α‐arylvinyldiazoesters and silanes has been developed by employing rhodium(I)/chiral diene complex as the catalyst. This protocol offers a catalytic asymmetric approach to various chiral silanes containing α‐arylvinyl functionality at room temperature with good enantiocontrol (89–99% ee). Transformation of the resulting enantiomerically enriched α‐arylvinyl‐α‐silyl esters led to a variety of other valuable building blocks. The deuterium kinetic isotope effect experiments revealed a rhodium(I)‐mediated concerted Si−H insertion mechanism. [ABSTRACT FROM AUTHOR]

The diversified synthesis of chiral fluorinated cyclobutane derivatives has remained a difficult task in synthetic chemistry. Herein, we present an approach for asymmetric hydroboration and formal hydrodefluorination of gem‐difluorinated cyclobutenes through rhodium catalysis, providing chiral gem‐difluorinated α‐boryl cyclobutanes and monofluorinated cyclobutenes with excellent regio‐ and enantioselectivity, respectively. The key to the success of the two transformations relies on an efficient, mild and highly selective rhodium‐catalyzed asymmetric hydroboration with HBPin (pinacolborane), in which the subsequent addition of a base, and a catalytic amount of palladium in some cases, results in the formation of formal hydrodefluorination products with the four‐membered ring retained. The obtained chiral gem‐difluorinated α‐boryl cyclobutanes are versatile building blocks that provide a platform for the synthesis of enantioenriched fluorinated cyclobutane derivatives to a great diversity. [ABSTRACT FROM AUTHOR]