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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]

Herein, we report the first example of Rh-catalyzed C(sp²)-H difluoroallylation of α,β-unsaturated amides with 3-bromo-3, 3-difluoropropene under mild conditions. The features of this protocol for difluoroallylation are unprecedented vinylic substrates, ethanol as a green solvent, good functional group and air compatibility, and scale-up synthesis with low catalyst loading. [ABSTRACT FROM AUTHOR]

The synthesis of housane derivatives from cyclopropenes is described. Under rhodium(II) catalysis, cyclopropenylvinyl carbinols can regioselectively generate a carbene intermediate which undergoes an intramolecular cyclopropanation to form a housane, a skeleton with similar ring strain as the cyclopropene precursor. The procedure shows a remarkable broad scope and efficiency. Moreover, the method served to prepare man‐made housane‐containing terpene derivatives, which are not accessible by Nature. [ABSTRACT FROM AUTHOR]

The formation of hydrido rhodium(I) complexes of the type [HRh(CO)3L] and [HRh(CO)2L2] from [Rh(acac)(CO)2]/L (L: bulky monophosphite ligand) requires a ligand‐to‐rhodium ratio [L]/[Rh] > 10 to prevent the possible partial generation of [Rh6(CO)16] under typical hydroformylation conditions. Significant fractions of formed [Rh6(CO)16] at lower ratios of [L]/[Rh] can be reactivated towards the hydrido complexes after the addition of the monophosphite ligand in the presence of synthesis gas. It was also found that [Rh6(CO)16] can be transformed by treatment with an excess of monophosphite ligand under inert gas to form a mononuclear complex of the type [L`Rh(CO)L] with an ortho‐metallated ligand. [ABSTRACT FROM AUTHOR]

The power and ability of catalysis to build multiple C−C bonds in a single step has had a transformative impact on organic synthesis. While the reactivity of organohalides with metal catalysts is widely appreciated, the related and more intricate reactivity of acid chlorides is less so, despite their use as common reagents in synthesis. Here, we review the transformations of acid chlorides in combination with unsaturated C−C bonds catalyzed by palladium, rhodium, or iridium and provide an outlook for future research opportunities. [ABSTRACT FROM AUTHOR]

The redox properties of half-sandwich rhodium complexes supported by 2,2′-bipyridyl (bpy) ligands can be readily tuned by selection of an appropriately substituted derivative of bpy, but the influences of single substituents on the properties of such complexes are not well documented, as disubstituted bpy variants are much more common. Here, the synthesis, characterization, and redox properties of two new [Cp*Rh] complexes (where Cp* is η5-1,2,3,4,5-pentamethylcyclopentadienyl) supported by the uncommon mono-substituted ligands 4-chloro-2,2′-bipyridyl (mcbpy) and 4-nitro-2,2′-bipyridyl (mnbpy) are reported. Single-crystal X-ray diffraction studies and related spectroscopic experiments confirm installation of the single substituents (–Cl and –NO2, respectively) on the bipyridyl ligands; the precursor monosubstituted ligands were prepared via a divergent route from unsubstituted bpy. Electrochemical studies reveal that each of the complexes undergoes an initial net two-electron reduction at potentials more positive than that associated with the parent unsubstituted complex of bpy, and that the complex supported by mnbpy can undergo a third, chemically reversible reduction at −1.62 V vs. ferrocenium/ferrocene. This redox behavior is consistent with inductive influences from the substituent groups on the supporting ligands, although the nitro group uniquely enables addition of a third electron. Spectrochemical studies carried out with UV-visible detection confirm the redox stoichiometry accessible to these platforms, highlighting the rich redox chemistry and tunable behavior of [Cp*Rh] complexes supported by bpy-type ligands. [ABSTRACT FROM AUTHOR]

The catalytic performance of a series of mono‐ and bimetallic Ir(I) and Rh(I) complexes bearing the (COC) bis‐triazolylidene ligand, coordinated in a bridging or chelating fashion, was evaluated in the cyclization of 4‐pentynoic acid. The chelated mononuclear cationic complex [Ir(cod)(COC)]PF6 (cod=1,5‐cyclooctadiene; COC=biscarbene ether) displayed the highest reaction rate for 4‐pentynoic acid to form γ‐methyl‐ene‐γ‐butyrolactone (5‐methylenedihydrofuran‐2(3H)‐one). Density Functional Theory calculations were carried out to rationalize the reaction mechanism which proceeds in three steps, namely coordination of the alkyne to the active catalyst followed by intramolecular cyclization and final reductive elimination. Its catalytic performance was further assessed against different substituted 4‐pentynoic acid derivatives. [ABSTRACT FROM AUTHOR]

Transition‐metal‐catalyzed enantioselective transformations of aryl/aryl carbene are inherently challenging due to the difficulty in distinguishing between two arene rings in the reaction process thus remain largely less explored. The few successful examples reported so far, without exception, have all been catalyzed by Rh(II)‐complexes. Herein, we describe our successful development of a novel cationic Rh(I)/chiral diene catalytic system capable of efficient enantioselective B−H and O−H insertions with diaryl diazomethanes, allowing the access to a broad range of gem‐diarylmethine boranes and gem‐diarylmethine ethers in good yields with high enantioselectivities. Notably, previously unattainable asymmetric diarylcarbene insertion into the O−H bond was achieved for the first time. A remarkable feature of this newly designed Rh(I)/diene catalyst bearing two ortho‐amidophenyl substitutents is that it can distinguish between two arene rings of the diaryl carbene through a stereochemically selective control of π–π stacking interactions. DFT calculations indicate that the rotation‐restricted conformation of Rh(I)/diene complex played an important role in the highly enantioselective carbene transformations. This work provides an interesting and unprecedented stereocontrol mode in diaryl metal carbene transformations. [ABSTRACT FROM AUTHOR]

This study investigated the electronic structure of single-atom Rhodium (Rh) and Iridium (Ir) adsorbed on defective and impurity-doped ZnO(0001) surfaces, and assessed their activity towards the CO oxidation reaction. Our findings reveal that surface impurities significantly influence the binding energies and electronic properties of the metal atoms, with Al and Cr serving as particularly effective promoters. While Rh and Ir acquire a positive charge upon incorporation on the unpromoted Zn(0001) surface, adsorption directly on the promoter results in a net negative charge, thus facilitating the activation of both CO and O2 species. These results highlight the potential of impurity-promoted ZnO surfaces in modulating and tailoring the electronic properties of SACs, which can be used for a rational design of active single-atom catalysts. [ABSTRACT FROM AUTHOR]

Functionalized 1,2,4,5-tetrasubstituted benzenes are synthetically difficult or laborious to access. The Rh-catalyzed [2+2+2] cycloaddition of a diyne and internal alkyne offers a seemingly straightforward route to these scaffolds; however, this has been largely restricted to alkynes bearing activating (coordinating) functional groups, with very few examples of unactivated alkynes. In this work, we disclose an assessment of Rh-catalyzed [2+2+2] cycloadditions employing unactivated internal alkynes, focusing on the structural diversity and compatibility of both alkyne and diyne components. The limitations of this method are disclosed, with exceptionally bulky alkynes and specific functional groups undergoing side reactions. Furthermore, the practicalities of gram-scale reactions and catalyst recovery/reuse are demonstrated. [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]

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Copyright of Nonferrous Metals (Extractive Metallurgy) is the property of Beijing Research Institute of Mining & Metallurgy Technology Group and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In the context of the growing importance of heterocyclic compounds across various disciplines, numerous strategies for their construction have emerged. Exploiting the distinctive properties of cyclopropenes, this study introduces an innovative approach for the synthesis of benzo‐fused five‐membered oxa‐ and aza‐heterocycles through a formal [4+1] cyclization and subsequent acid‐catalyzed intramolecular O‐ to N‐ rearrangement. These transformations exhibit mild reaction conditions and a wide substrate scope. The applications in the late‐stage modification of complex molecules and in the synthesis of a potential PD‐L1 gene down‐regulator, make this method highly appealing in related fields. Combined experimental mechanistic studies and DFT calculations demonstrate Rh(III)‐mediated sequential C─H coupling/π‐allylation/dynamically favorable O‐attack route. [ABSTRACT FROM AUTHOR]

The intramolecular Buchner reaction is a powerful transformation able to dearomatize benzenic rings. However, the competitive C−H insertion of the carbene moiety into benzylic positions still remains a limitation, and the reasons governing this uncomplete chemoselectivity are poorly understood. The carbene substitution, in particular, has been observed to influence the selectivity strongly, though the currently proposed explanation relying on the electrophilicity of the metallocarbene hardly describes some experimental results reported in the literature. In this article, we present our experimental observations of intramolecular rhodium‐catalyzed Buchner reactions, combined with DFT calculations on selected carbene substituents, to propose a complementary explanation for the observed chemoselectivity modification. [ABSTRACT FROM AUTHOR]

In this study, we report a Rh(I)/dppf catalytic system that can tune the regioselectivity of methylenecyclobutanes. Under the optimal reaction conditions, a series of 1,3‐disubstituted cyclobutanes were prepared in high yields (up to 95%) with excellent regioselectivity (>20:1 r.r.). Scale‐up synthesis of the cyclobutane product at a low catalyst loading (2 mol%) demonstrates the robustness of this dppf‐controlled hydroacylation. [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]

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]

Controlling the polymorphism of metal nanocrystals is a promising strategy for enhancing properties and discovering new phenomena. However, previous studies on Rh nanocrystals have focused on their thermodynamically stable face‐centered‐cubic (fcc) phase. Herein, a facile synthesis of Rh‐based nanocrystals featuring the metastable hexagonal close‐packed (hcp) phase is reported by using Ru seeds in their native hcp phase to template the deposition of Rh atoms. The success of such phase‐controlled synthesis relies on the templating effect promoted by the small lattice mismatch between Ru and Rh and the slow dropwise titration of the precursor at an elevated temperature, ensuring the layer‐by‐layer growth mode and thus the formation of a conformal hcp‐Rh shell. Faster injection rate of Rh(III) precursor leads to the formation of a rough Rh shell in the conventional fcc phase due to accelerated reaction kinetics. Considering both thermodynamic and kinetic aspects of this system, the hcp‐Rh phase is favored when the low surface energy from smooth overlayers balances the high bulk energy of the metastable phase, achieved through tight control of reaction rates and deposition patterns. These Ruhcp@Rhhcp core–shell nanocrystals demonstrate thermal stability up to 400 °C, while exhibiting higher catalytic activity toward ethanol oxidation reaction compared to Ruhcp@Rhfcc counterparts. [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]

Enantiopure chiral-at-metal rhodium(III) unsaturated 16e complexes have been obtained from racemic [Rh(SiN)2Cl] (SiN= 8-(dimethylsilyl)quinoline) using a readily accessible chiral spiroborate as chiral resolution agent. This strategy allows an easy access to enantiopure neutral Δ/Λ-Rh(SiN)2Cl and cationic Δ/Λ-Rh(SiN)2[BAr4F] unsaturated complexes, wherein rhodium(III) is coordinated to two inert silylquinoline ligands in a propeller-like arrangement. [ABSTRACT FROM AUTHOR]

ABSTRACT NHC pincers (NHC = N‐heterocyclic carbene), which combine the structural benefits of both carbenes and pincer platforms, have shown diverse applications, spanning from fundamental organometallic chemistry to homogeneous catalysis. Although aryl‐bridged bis(NHCs) represent the earliest developed and most studied type of NHC pincers, such [C^C^C]‐platforms have been underutilized in the synthesis of rhodium complexes. In this study, we present several less explored organorhodium(III) complexes featuring [C^C^C]‐pincers. Their synthetic route via a convenient oxidative addition approach has been explored, and the obtained cyclorhodium(III) complexes show versatile coordination geometry (square pyramidal or octahedral). Additionally, these cyclorhodium(III) complexes exhibit very different regioselectivity in catalytic alkyne hydrosilylations compared to known Rh(III) NHC catalytic systems. Finally, a few mechanistic studies have also been conducted, and a plausible mechanism was proposed. [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]

Starting from N‐acyl sulfonimidamides, mechanochemically generated rhodium nitrenoids undergo intramolecular N−O couplings to provide unprecedented 1,3,2,4‐oxathiadiazole 3‐oxides in good to excellent yields. The cyclization proceeds efficiently with a catalyst loading of only 0.5 mol % in the presence of phenyliodine(III) diacetate (PIDA) as oxidant. Neither an inert atmosphere nor additional heating is required in this solvent‐free procedure. Under heat or blue light, the newly formed five‐membered heterocycles function as nitrene precursors reacting with sulfoxides as exemplified by the imidation of dimethyl sulfoxide. [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]

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]

Copyright of Nuclear Safety is the property of Nuclear & Radiation Safety Center and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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]

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]

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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Copyright of Inorganic Chemicals Industry is the property of Editorial Office of Inorganic Chemicals Industry and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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]

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]

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]

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]

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]