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o‐Aminoazotoluene (OAT), capable of photoisomerization, and o‐vanillin, a potent comutagen, have been used to synthesize a new ligand, HL, [C6H4(CH3)N=NC6H3(CH3)N=CHC6H3(OH)(OCH3)], which, upon complexation with copper(II), results in a new copper(II) complex‐Cu(L)2, [Cu{C6H4(CH3)N=NC6H3(CH3)N=CHC6H3(OCH3)O}2]. Both HL and Cu(L)2 have been characterized by single‐crystal X‐ray diffraction measurements along with other analytical techniques, for example, IR spectroscopy, NMR spectroscopy, UV–Vis spectroscopy, elemental analysis and mass spectrometry. These compounds were tested with different in vitro anticancer assay as well as with in silico studies. A comparative study has been demonstrated on anticancer activity of HL and Cu(L)2 with the ligand HAZ, {C6H5N=NC6H4N=CHC6H3(OH)(OCH3)} and its Cu‐complex, [Cu(AZ)2, Cu{C6H5N=NC6H4N=CHC6H3(OCH3)O}2]. The sensing properties of HAZ, along with the synthesis and structural properties of both HAZ and Cu(AZ)2, have been reported by our group earlier. Cytotoxicity measurements on MCF7 cell lines show that Cu(L)2 and Cu(AZ)2 have higher anticancer activity than their corresponding ligands. The apoptotic effect of Cu‐complex was studied through nuclear fragmentation assay and AO/EB dual‐staining assay on MCF7 cell line. The IC50 value of Cu(L)2 in 0.01% DMSO/water after 24‐h treatment was found 4.2 μM, which is one of the lowest values with this response time compared to the other analogous anticancer compounds. Finally, we have evaluated the expression of hERα protein with respect to Cu‐complexes, and it was observed that Cu(L)2 caused more down‐regulation of hERα as compared to Cu(AZ)2. [ABSTRACT FROM AUTHOR]

The synthesis of lanthanide‐based organometallic sandwich compounds is very appealing regarding their potential for single‐molecule magnetism. Here, it is exploited by on‐surface synthesis to design unprecedented lanthanide‐directed organometallic sandwich complexes on Au(111). The reported compounds consist of Dy or Er atoms sandwiched between partially deprotonated hexahydroxybenzene molecules, thus introducing a distinct family of homoleptic organometallic sandwiches based on six‐membered ring ligands. Their structural, electronic, and magnetic properties are investigated by scanning tunneling microscopy and spectroscopy, X‐ray absorption spectroscopy, X‐ray linear and circular magnetic dichroism, and X‐ray photoelectron spectroscopy, complemented by density functional theory‐based calculations. Both lanthanide complexes self‐assemble in close‐packed islands featuring a hexagonal lattice. It is unveiled that, despite exhibiting analogous self‐assembly, the erbium‐based species is magnetically isotropic, whereas the dysprosium‐based compound features an in‐plane magnetization. [ABSTRACT FROM AUTHOR]

We conducted a joint synthetic, spectroscopic and computational study to explore the reactivity towards cyanide (from Bu4NCN) of a series of dinuclear complexes based on the M2Cp2(CO)3 scaffold (M = Fe, Ru; Cp = η5-C5H5), namely [M2Cp2(CO)2(µ-CO){µ,η1:η2-CH=C=CMe2}]BF4 (1Fe-Ru), [Ru2Cp2(CO)2(µ-CO){µ,η1:η2-C(Ph)=CHPh}]BF4 (2Ru) and [M2Cp2(CO)2(µ-CO){µ-CN(Me)(R)}]CF3SO3 (3Fe-Ru). While the reaction of 1Fe with Bu4NCN resulted in prevalent allenyl deprotonation, preliminary CO-NCMe substitution in 1Ru enabled cyanide addition to both the allenyl ligand (resulting in the formation of a h1:h2-allene derivative, 5A) and the two metal centers (affording 5B1 and 5B2). The mixture of 5B1-2 was rapidly converted into 5A in heptane solution at 100 °C, with 5A being isolated with a total yield of 60%. Following carbonyl-chloride substitution in 2Ru, CN− was incorporated as a terminal ligand upon Cl− displacement, to give the alkenyl complex 6 (84%). The reactivity of 3Fe and 3Ru is strongly influenced by both the metal element, M, and the aminocarbyne substituent, R. Thus, 7aRu was obtained with a 74% yield from cyanide attack on the carbyne in 3aRu (R = Cy, cyclohexyl), whereas the reaction involving the diiron counterpart 3aFe yielded an unclean mixture of the metastable 7aFe and the CO/CN− substitution product 8aFe. The cyano-alkylidene complexes 7aRu (R = Cy) and 7bFe (R = Me) underwent CO loss and carbene to carbyne conversion in isopropanol at 60–80 °C, giving 8aRu (48%) and 8bFe (71%), respectively. The novel compounds 5A, 5B1-2, 6 and 7aRu were characterized by IR and NMR spectroscopy, with the structure of 7aRu further elucidated by single crystal X-ray diffraction analysis. Additionally, the DFT-optimized structures of potential isomers of 5A, 5B1-2 and 6 were calculated. [ABSTRACT FROM AUTHOR]

The flash organometallic catalysis is a new concept that refers to the study of fast and controlled organometallic catalytic reactions by using microfluidic devices. Flash reactions' kinetics (ms‐s scale) is often ignored due to the lack of proper research tool in organometallic chemistry. The development of microfluidic systems offers the opportunity to discover under‐studied mechanisms and new reactions. In this concept, the basic theory of kinetic measurement in a microreactor is briefly reviewed and then two examples on studying flash organometallic catalytic transformation are introduced. One example is the discovery of a highly active palladium catalytic species for Suzuki Coupling and the other example is the study of a neglected isomerization catalytic cycle with a time scale of seconds before isomerization‐hydroformylation by customized microfluidic devices. The last part is summary and prospect of this new area. Customizing a microfluidic device with good engineering design for a target reaction supports flash reactions' kinetic experimentation and could become a general strategy in chemistry lab. [ABSTRACT FROM AUTHOR]

Molecular junctions, which involve sandwiching molecular structures between electrodes, play a crucial role in molecular electronics. Recent advances in this field have revealed the vital role of organometallic chemistry in the investigation of molecular junctions, which has added to their well-known contributions to catalysis and materials chemistry. This review summarizes the recent examples of organometallic chemistry applications in molecular junctions, which can be categorized into three types, i.e., class I encompassing molecular junctions with bridging organometallic complexes, class II involving molecular junctions with covalent and noncovalent metal electrode-carbon bonds, and class III comprising organometallic reactions within molecular junctions. [ABSTRACT FROM AUTHOR]

The field of coordination chemistry has evolved to intersect with organic chemistry and biochemistry, giving rise to the disciplines of organometallic and bioinorganic chemistry. Nuclear magnetic resonance (NMR) spectroscopy can be applied for characterizing transition metal complexes, spanning both diamagnetic and paramagnetic complexes prevalent in organometallic compounds and metalloproteins. This review offers a comprehensive overview of a wide variety of characterization techniques, ranging from basic 1H and 13C NMR spectroscopy to advanced methods such as heteronuclear experiments, polarization transfer techniques, relaxometry, and multidimensional NMR spectroscopy. The diverse array of NMR spectroscopic methods outlined here promises to enhance our comprehension of transition metal complexes, facilitating the development of innovative catalysts and therapeutics. [ABSTRACT FROM AUTHOR]

By exploiting the electronic capabilities of the N‐heterocyclic boryloxy (NHBO) ligand, we have synthesized “naked” acyclic gallyl [Ga{OB(NDippCH)2}2]− and indyl [In{OB(NDippCH)2}2]− anions (as their [K(2.2.2‐crypt)]+ salts) through K+ abstraction from [KGa{OB(NDippCH)2}2] and [KIn{OB(NDippCH)2}2] using 2.2.2‐crypt. These systems represent the first O‐ligated gallyl/indyl systems, are ultimately accessed from cyclopentadienyl GaI/InI precursors by substitution chemistry, and display nucleophilic reactivity which is strongly influenced by the presence (or otherwise) of the K+ counterion. [ABSTRACT FROM AUTHOR]

Typically reactions of N‐heterocyclic carbenes with transition metals are straightforward and require a carbene salt, a base strong enough to deprotonate such a salt and a metal. Yet when carbene precursors are in the form of triazolium salts, reaction may not proceed as easily as expected. In our work, we intended to obtain a triazolylidene complex of iron(II) chloride, but due to the presence of small amounts of water in the tetrahydrofuran solvent used, bis(acetonitrile)tetrakis(1‐benzyl‐1H‐1,2,4‐triazole‐κN4)iron(II) μ‐oxido‐bis[trichloridoferrate(III)] acetonitrile disolvate, [Fe(C9H9N3)4(CH3CN)2][Fe2Cl6O]·2CH3CN – an interesting anion with a linear geometry of the O atom – was formed instead of the iron carbene complex. Reaction proceeded via cleavage of the alkyl N‐substituent of the triazolium salt. The formation of the product was confirmed by X‐ray crystallography. The crystal structure and possible reaction pathways are discussed. [ABSTRACT FROM AUTHOR]

N-Heteroaromatics are key elements of pharmaceuticals, agrochemicals, and materials. N-Heteroarynes provide a scaffold to build these essential molecules but are underused because five-membered N-heteroarynes have been largely inaccessible on account of the strain of a triple bond in that small of a ring. On the basis of principles of metal-ligand interactions that are foundational to organometallic chemistry, in this work we report the stabilization of five-membered N-heteroarynes in the nickel coordination sphere. A series of 1,2-bis(dicyclohexylphosphino)ethane nickel 7-azaindol-2,3-yne complexes were synthesized and characterized crystallographically and spectroscopically. Ambiphilic reactivity of the nickel 7-azaindol-2,3-yne complexes was observed with multiple nucleophilic, electrophilic, and enophilic coupling partners. [ABSTRACT FROM AUTHOR]

In the past 18 years, metal‐catalyzed deallylation has proven a useful tool for studying biological processes in cellulo and in the early development of innovative therapeutic catalytic strategies. This reaction is catalyzed by Ru‐piano stool complexes and has been reported to be compatible with air, water, and thiol‐containing compounds such as glutathione. However, little is known about the true influence of biological components on the outcome of this reaction. The results presented herein reveal that the co‐solvent used in the reaction affects the complex's stability and activity in air, while the presence of glutathione contributes to minimizing the formation of N‐allylated by‐products. In addition, we studied the effect of air on the Ru‐catalyzed deallylation. Importantly, we found that, in the presence of air, the complex is deactivated and oxidizes glutathione into its disulfide. [ABSTRACT FROM AUTHOR]

A Surface OrganoMetallic Chemistry (SOMC) approach is used to prepare a novel hafnium‐iridium catalyst immobilized on silica, HfIr/SiO2, featuring well‐defined [≡SiOHf(CH2tBu)2(μ‐H)3IrCp*] surface sites. Unlike the monometallic analogous materials Hf/SiO2 and Ir/SiO2, which promote n‐pentane deuterogenolysis through C−C bond scission, we demonstrate that under the same experimental conditions (1 bar D2, 250 °C, 3 h, 0.5 mol %), the heterobimetallic catalyst HfIr/SiO2 is highly efficient and selective for the perdeuteration of alkanes with D2, exemplified on n‐pentane, without substantial deuterogenolysis (<2 % at 95 % conversion). Furthermore this HfIr/SiO2 catalyst is robust and can be re‐used several times without evidence of decomposition. This represents substantial advance in catalytic H/D isotope exchange (HIE) reactions of C(sp3)−H bonds. [ABSTRACT FROM AUTHOR]

A Surface OrganoMetallic Chemistry (SOMC) approach is used to prepare a novel hafnium‐iridium catalyst immobilized on silica, HfIr/SiO2, featuring well‐defined [≡SiOHf(CH2tBu)2(μ‐H)3IrCp*] surface sites. Unlike the monometallic analogous materials Hf/SiO2 and Ir/SiO2, which promote n‐pentane deuterogenolysis through C−C bond scission, we demonstrate that under the same experimental conditions (1 bar D2, 250 °C, 3 h, 0.5 mol %), the heterobimetallic catalyst HfIr/SiO2 is highly efficient and selective for the perdeuteration of alkanes with D2, exemplified on n‐pentane, without substantial deuterogenolysis (<2 % at 95 % conversion). Furthermore this HfIr/SiO2 catalyst is robust and can be re‐used several times without evidence of decomposition. This represents substantial advance in catalytic H/D isotope exchange (HIE) reactions of C(sp3)−H bonds. [ABSTRACT FROM AUTHOR]

This mini-review offers a comprehensive overview of the advancements made over the last three years in utilizing highly polar s-block organometallic reagents (specifically, RLi, RNa and RMgX compounds) in organic synthesis run under bench-type reaction conditions. These conditions involve exposure to air/moisture and are carried out at room temperature, with the use of sustainable solvents as reaction media. In the examples provided, the adoption of Deep Eutectic Solvents (DESs) or even water as non-conventional and protic reaction media has not only replicated the traditional chemistry of these organometallic reagents in conventional and toxic volatile organic compounds under Schlenk-type reaction conditions (typically involving low temperatures of −78 °C to 0 °C and a protective atmosphere of N2 or Ar), but has also resulted in higher conversions and selectivities within remarkably short reaction times (measured in s/min). Furthermore, the application of the aforementioned polar organometallics under bench-type reaction conditions (at room temperature/under air) has been extended to other environmentally responsible reaction media, such as more sustainable ethereal solvents (e.g., CPME or 2-MeTHF). Notably, this innovative approach contributes to enhancing the overall sustainability of s-block-metal-mediated organic processes, thereby aligning with several key principles of Green Chemistry. [ABSTRACT FROM AUTHOR]

Palladium‐catalyzed Suzuki‐Miyaura and Buchwald‐Hartwig cross‐coupling reactions have become indispensable tools in the synthesis of otherwise inaccessible compounds because of the efficient, catalytic nature of these styles of reactions. The development of novel monophosphine ligands to achieve the cross‐coupling of substrates that are generally unreactive under standard conditions has developed into an extremely important area of research in the field of organometallic chemistry. Herein, we show the use of an imidazopyridine monophosphine ligand JagPhos I in the Suzuki‐Miyaura palladium‐catalyzed cross‐coupling reaction to deliver sterically‐hindered biaryls and unsymmetrical biheterocycles. We also report the scope and limitations of imidazopyridine monophosphine ligand JagPhos II in the Buchwald‐Hartwig amination reactions of (hetero)aryl halides with anilines, secondary amines, and primary amines. [ABSTRACT FROM AUTHOR]

The reactivity and selectivity of a transition metal catalyst is intimately related to its ligand‐sphere geometry, and, in many cases, the ideal ligand geometry for one step of a catalytic cycle is poorly matched to the ideal ligand geometry for another. For this reason, methods for reversibly modulating ligand geometry on the time scale of catalytic turnover or monomer enchainment are highly desirable. Mechanical force represents a heretofore untapped approach to modulate catalyst geometry and/or reactivity, with the potential to do so on the timescale of catalytic turnover or monomer enchainment. Macroscopic mechanical forces are large, directional and localized to an extent that differentiates them from other forms of energy input such as heat or light. In this Concept, we describe our efforts to address the fundamental challenges associated with force‐modulated transition metal catalysis by employing molecular force probe ligands comprising a stiff stilbene photoswitch tethered to rotationally flexible biaryl bisphosphine ligand. Our efforts to date include the modulation of catalytic activity through force‐mediated ligand perturbations, quantification of the force‐coupled ligand effects on the energetics of elementary organometallic transformations, and evaluation of the mechanisms of force transduction in these systems. [ABSTRACT FROM AUTHOR]

Whereas indications of radical reactivity in bismuth compounds can be traced back to the 19th century, the preparation and characterization of both transient and persistent bismuth‐radical species has only been established in recent decades. These advancements led to the emergence of the field of bismuth radical chemistry, mirroring the progress seen for other main‐group elements. The seminal and fundamental studies in this area have ultimately paved the way for the development of catalytic methodologies involving bismuth‐radical intermediates, a promising approach that remains largely untapped in the broad landscape of synthetic organic chemistry. In this review, we delve into the milestones that eventually led to the present state‐of‐the‐art in the field of radical bismuth chemistry. Our focus aims at outlining the intrinsic discoveries in fundamental inorganic/organometallic chemistry and contextualizing their practical applications in organic synthesis and catalysis. [ABSTRACT FROM AUTHOR]

Whereas indications of radical reactivity in bismuth compounds can be traced back to the 19th century, the preparation and characterization of both transient and persistent bismuth‐radical species has only been established in recent decades. These advancements led to the emergence of the field of bismuth radical chemistry, mirroring the progress seen for other main‐group elements. The seminal and fundamental studies in this area have ultimately paved the way for the development of catalytic methodologies involving bismuth‐radical intermediates, a promising approach that remains largely untapped in the broad landscape of synthetic organic chemistry. In this review, we delve into the milestones that eventually led to the present state‐of‐the‐art in the field of radical bismuth chemistry. Our focus aims at outlining the intrinsic discoveries in fundamental inorganic/organometallic chemistry and contextualizing their practical applications in organic synthesis and catalysis. [ABSTRACT FROM AUTHOR]

Arylation of gold holds paramount importance in the domain of organometallic chemistry; however, the exploration of arylgold nanoclusters remains in its infancy primarily due to the synthetic challenge. Here, we present a facile and effective arylation strategy to directly synthesize two arylgold nanoclusters (Au44a and Au44b), by using tetraarylborates, capable of transferring aryl fragments to metal centers. X-ray crystallography reveals that both Au44 nanoclusters contain an Au44 kernel co-protected by six aryl groups, two tetrahydrothiophene, and 16 alkynyl-ether ligands, the latter is generated in situ through Williamson ether reaction during the assembly processes. Notably, Au44 nanoclusters exhibit near-infrared (NIR) phosphorescence (λmax = 958 nm) and microsecond radiative relaxation at ambient condition, which is a thermal-controlled single/dual-channel phosphorescent emission revealed by temperature-dependent NIR, time-resolved emission, and femtosecond/nanosecond transition absorption spectra. This work represents a breakthrough in using aryl as protective ligands for the construction of gold nanoclusters, which is poised to have a transformative impact on organometallic nanoclusters. [ABSTRACT FROM AUTHOR]

Beryllium possesses a unique amalgamation of characteristics, its electronegativity included, that not only make it a vital component in a wide range of technical sectors and consumer industries, but also make it an interesting candidate for forming covalently bonded compounds. However, the extremely toxic nature of beryllium, which can cause chronic beryllium disease, has limited the exploration of its chemistry, making beryllium one of the least studied (non-radioactive) elements. The development of selective chelating ligands, sterically encumbered substituents and, moreover, the boom of N-heterocyclic carbenes in organometallic chemistry and main group chemistry has revived the interest in beryllium chemistry. Therefore, some quite remarkable progress in the coordination and organometallic chemistry of beryllium has been made in the last two decades. For example, low oxidation state beryllium compounds, antiaromatic/aromatic beryllium compounds, where beryllium is involved in π-electron delocalization, and the isolation of beryllium-beryllium bonded species have all been achieved. This article provides an oversight over the recent developments in the organometallic chemistry of beryllium. [ABSTRACT FROM AUTHOR]

Wide applications of anhydrous rare‐earth (RE) trichlorides RECl3 in organometallic chemistry, for the synthesis of optical and magnetic materials, and as catalysts require a facile approach for their synthesis. The known methods use or produce toxic substances, are complicated and have limited reliability and upscaling. It has been shown that task‐specific ionic liquids (ILs) can dissolve many metal oxides without special reaction conditions at moderate temperature, making the metals accessible to downstream chemistry. Using imidazolium chloridoaluminate ILs, pure crystalline anhydrous RECl3 (RE=La−Nd, Sm−Dy) can be synthesized in one step from RE oxides in high yield. The Lewis acidic IL acts as solvent and reaction partner. The by‐product [Al4O2Cl10]2−, which was detected spectroscopically, remains in solution. The reacted IL can be removed quantitatively by washing. ILs with various imidazolium cations and AlCl3 content and the effect of temperature and reaction time were tested. [ABSTRACT FROM AUTHOR]

Wide applications of anhydrous rare‐earth (RE) trichlorides RECl3 in organometallic chemistry, for the synthesis of optical and magnetic materials, and as catalysts require a facile approach for their synthesis. The known methods use or produce toxic substances, are complicated and have limited reliability and upscaling. It has been shown that task‐specific ionic liquids (ILs) can dissolve many metal oxides without special reaction conditions at moderate temperature, making the metals accessible to downstream chemistry. Using imidazolium chloridoaluminate ILs, pure crystalline anhydrous RECl3 (RE=La−Nd, Sm−Dy) can be synthesized in one step from RE oxides in high yield. The Lewis acidic IL acts as solvent and reaction partner. The by‐product [Al4O2Cl10]2−, which was detected spectroscopically, remains in solution. The reacted IL can be removed quantitatively by washing. ILs with various imidazolium cations and AlCl3 content and the effect of temperature and reaction time were tested. [ABSTRACT FROM AUTHOR]

Computational studies of the coordination chemistry and bonding of lanthanides have grown in recent decades as the need for understanding the distinct physical, optical, and magnetic properties of these compounds increased. Density functional theory (DFT) methods offer a favorable balance of computational cost and accuracy in lanthanide chemistry and have helped to advance the discovery of novel oxidation states and electronic configurations. This Frontier article examines the scope and limitations of DFT in interpreting structural and spectroscopic data of low-valent lanthanide complexes, elucidating periodic trends, and predicting their properties and reactivity, presented through selected examples. [ABSTRACT FROM AUTHOR]

The ethylene polymerization Phillips catalyst has been employed for decades and is central to the polymer industry. While Cr(III) alkyl species are proposed to be the propagating sites, there is so far no direct experimental evidence for such proposal. In this work, by coupling Surface organometallic chemistry, EPR spectroscopy, and machine learning‐supported XAS studies, we have studied the electronic structure of well‐defined silica‐supported Cr(III) alkyls and identified the presence of several surface species in high and low‐spin states, associated with different coordination environments. Notably, low‐spin Cr(III) sites are shown to participate in ethylene polymerization, indicating that similar Cr(III) alkyl species could be involved in the related Phillips catalyst. [ABSTRACT FROM AUTHOR]

This review article provides a comprehensive overview of recent advancements in the realm of cyclophosphazenes, encompassing their preparation methodologies, distinctive properties, and diverse applications. The synthesis approaches are explored, highlighting advancements in the preparation of these cyclic compounds. The discussion extends to the distinctive properties exhibited by cyclophosphazenes, including thermal stability characteristics, and other relevant features. Furthermore, we examine the broad spectrum of applications for cyclophosphazenes in various fields, such as coatings, adhesives, composites, extractants, metal complexes, organometallic chemistry, medicine, and inorganic chemistry. This review aims to offer insights into the evolving landscape of cyclophosphazenes and their ever-expanding roles in contemporary scientific and technological arenas. Future possibilities are emphasized, and significant research data shortages are identified. [ABSTRACT FROM AUTHOR]

The ethylene polymerization Phillips catalyst has been employed for decades and is central to the polymer industry. While Cr(III) alkyl species are proposed to be the propagating sites, there is so far no direct experimental evidence for such proposal. In this work, by coupling Surface organometallic chemistry, EPR spectroscopy, and machine learning‐supported XAS studies, we have studied the electronic structure of well‐defined silica‐supported Cr(III) alkyls and identified the presence of several surface species in high and low‐spin states, associated with different coordination environments. Notably, low‐spin Cr(III) sites are shown to participate in ethylene polymerization, indicating that similar Cr(III) alkyl species could be involved in the related Phillips catalyst. [ABSTRACT FROM AUTHOR]

Cobalt‐based catalysts are well‐known to convert syngas into a variety of Fischer–Tropsch (FTS) products depending on the various reaction parameters, in particular particle size. In contrast, the reactivity of these particles has been much less investigated in the context of CO2 hydrogenation. In that context, Surface organometallic chemistry (SOMC) was employed to synthesize highly dispersed cobalt nanoparticles (Co‐NPs) with particle sizes ranging from 1.6 to 3.0 nm. These SOMC‐derived Co‐NPs display significantly different catalytic performances under CO2 hydrogenation conditions: while the smallest cobalt nanoparticles (1.6 nm) catalyze mainly the reverse water‐gas shift (rWGS) reaction, the larger nanoparticles (2.1–3.0 nm) favor the expected methanation activity. Operando X‐ray absorption spectroscopy shows that the smaller cobalt particles are fully oxidized under CO2 hydrogenation conditions, while the larger ones remain mostly metallic, paralleling the observed difference of catalytic performances. This fundamental shift of selectivity, away from methanation to reverse water‐gas shift for the smaller nanoparticles is noteworthy and correlates with the formation of CoO under CO2 hydrogenation conditions. [ABSTRACT FROM AUTHOR]

Cobalt‐based catalysts are well‐known to convert syngas into a variety of Fischer–Tropsch (FTS) products depending on the various reaction parameters, in particular particle size. In contrast, the reactivity of these particles has been much less investigated in the context of CO2 hydrogenation. In that context, Surface organometallic chemistry (SOMC) was employed to synthesize highly dispersed cobalt nanoparticles (Co‐NPs) with particle sizes ranging from 1.6 to 3.0 nm. These SOMC‐derived Co‐NPs display significantly different catalytic performances under CO2 hydrogenation conditions: while the smallest cobalt nanoparticles (1.6 nm) catalyze mainly the reverse water‐gas shift (rWGS) reaction, the larger nanoparticles (2.1–3.0 nm) favor the expected methanation activity. Operando X‐ray absorption spectroscopy shows that the smaller cobalt particles are fully oxidized under CO2 hydrogenation conditions, while the larger ones remain mostly metallic, paralleling the observed difference of catalytic performances. This fundamental shift of selectivity, away from methanation to reverse water‐gas shift for the smaller nanoparticles is noteworthy and correlates with the formation of CoO under CO2 hydrogenation conditions. [ABSTRACT FROM AUTHOR]

Using the [3+2] cycloaddition reaction of [HC≡C−GePh2−]2 (1) and a number of RCH2N3, this work described the synthesis of a series of novel heterocyclic digermanes, bitriazoles [1,4‐C2HN3(CH2R)GePh2−]2, 2–12 (R=Ph, p‐Tol, p‐C6H4NMe2, p‐C6H4OMe, p‐C6H4Br, m‐C6H4NO2, 2‐Naphth, CH2‐p‐OC6H4CHO, CH2‐p‐OC6H4COOMe, CH2P(O)(OEt)2, COOEt), difficult to produce by other methods. The structural peculiarities of these compounds were studied in detail by NMR spectroscopy and by XRD analysis (for 6, 9 and 10). The properties of 1–12 were studied by UV/vis and luminescence emission spectroscopy, electrochemistry and DFT calculations, indicating an effective conjugation in their molecules. [ABSTRACT FROM AUTHOR]

Inorganic chemistry at the interface with other scientific disciplines has led to the emergence of several new fields like organometallic chemistry, bio-inorganic chemistry, solid-state chemistry, environmental chemistry, etc. In the past few decades, it has made inroads into yet another dimension of immense relevance, i.e., nanoscience and nanotechnology. Accordingly, a number of approaches for the synthesis of nanomaterials have been developed. Of these routes, the molecular precursor route based on organometallic or metallo-organic compounds has emerged as a versatile approach for the synthesis of both nanocrystals and thin films. In this essay an attempt has been made to present an overview of utility of organometallic or metallo-organic compounds as molecular precursors for the synthesis of nanomaterials with reference to catalysis and materials science. Applications of metal nanoparticles (NPs) and metal chalcogenide NPs, generated through the molecular precursor route, in catalysis have been discussed. Synthesis of ternary and quaternary metal chalcogenide nanomaterials by the molecular precursor route has been outlined. [ABSTRACT FROM AUTHOR]

Black phosphorus (bP) is a two‐dimensional van der Waals material unique in its potential to serve as a support for single‐site catalysts due to its similarity to molecular phosphines, ligands quintessential in homogeneous catalysis. However, there is a scarcity of synthetic methods to install single metal centers on the bP lattice. Here, we demonstrate the functionalization of bP nanosheets with molecular Re and Mo complexes. A suite of characterization techniques, including infrared, X‐ray photoelectron and X‐ray absorption spectroscopy as well as scanning transmission electron microscopy corroborate that the functionalized nanosheets contain a high density of discrete metal centers directly bound to the bP surface. Moreover, the supported metal centers are chemically accessible and can undergo ligand exchange transformations without detaching from the surface. The steric and electronic properties of bP as a ligand are estimated with respect to molecular phosphines. Sterically, bP resembles tri(tolyl)phosphine when monodentate to a metal center, and bis(diphenylphosphino)propane when bidentate, whereas electronically bP is a σ‐donor as strong as a trialkyl phosphine. This work is foundational in elucidating the nature of black phosphorus as a ligand and underscores the viability of using bP as a basis for single‐site catalysts. [ABSTRACT FROM AUTHOR]

Black phosphorus (bP) is a two‐dimensional van der Waals material unique in its potential to serve as a support for single‐site catalysts due to its similarity to molecular phosphines, ligands quintessential in homogeneous catalysis. However, there is a scarcity of synthetic methods to install single metal centers on the bP lattice. Here, we demonstrate the functionalization of bP nanosheets with molecular Re and Mo complexes. A suite of characterization techniques, including infrared, X‐ray photoelectron and X‐ray absorption spectroscopy as well as scanning transmission electron microscopy corroborate that the functionalized nanosheets contain a high density of discrete metal centers directly bound to the bP surface. Moreover, the supported metal centers are chemically accessible and can undergo ligand exchange transformations without detaching from the surface. The steric and electronic properties of bP as a ligand are estimated with respect to molecular phosphines. Sterically, bP resembles tri(tolyl)phosphine when monodentate to a metal center, and bis(diphenylphosphino)propane when bidentate, whereas electronically bP is a σ‐donor as strong as a trialkyl phosphine. This work is foundational in elucidating the nature of black phosphorus as a ligand and underscores the viability of using bP as a basis for single‐site catalysts. [ABSTRACT FROM AUTHOR]

The bis(azolium) salt [L1‐H2]Br2 was found to serve as a suitable platform for accessing the heterobimetallic IrIII‐M (M=PdII/AuI) and PdII‐IrIII complexes. Initially, selective mono‐metalation of [L1‐H2]Br2 yielded an orthometalated IrIII‐ or non‐orthometalated PdII‐complex. Sequential metalation of the mono‐IrIII complex resulted in the formation of heterobimetallic IrIII‐PdII/AuI complexes. Similarly, a distinct heterobimetallic PdII‐IrIII complex was synthesized starting from the mono‐PdII complex. Further, the corresponding homobimetallic IrIII‐IrIII and PdII‐PdII complexes were directly obtained from [L1‐H2]Br2. Additionally, monometallic PdII and IrIII analogues were synthesized from [L2‐H]Br and [L3‐H]Br, respectively. The heterobimetallic IrIII‐PdII and PdII‐IrIII complexes were then evaluated as catalysts in various one‐pot tandem catalytic reactions in which they demonstrated superior activity than the mixtures of both their corresponding homobimetallic IrIII‐IrIII/PdII‐PdII and monometallic IrIII/PdII counterparts, under the constant concentrations of metal centers. Moreover, while comparing complexes IrIII‐PdII and PdII‐IrIII, the former exhibits higher activity in all the studied reactions. All these findings suggest the presence of some form of cooperativity between the two metal centers (Ir and Pd) connected by a single ligand framework in IrIII‐PdII and PdII‐IrIII complex, with IrIII‐PdII displaying better cooperativity that has been validated by electrochemical, NMR, and DFT studies. [ABSTRACT FROM AUTHOR]

A series of pseudorotaxanes with supramolecular organometallic silver(I) and gold(I) pillarplexes acting as rings and different α,ω‐dicarboxylic acids as axle components are reported. The successful formation of the host‐guest complexes is shown by 1H NMR spectroscopy and respective NMR titration. Additional evaluation with ITC titration experiments yielded dissociation constants (Kd) ranging from 10−5 to 10−7 M. Single‐crystal X‐Ray diffraction analysis reveals a particularly exciting pore alignment of different examples in the solid state depending on the length of the guest. The work highlights, that dicarboxylic acids can penetrate the tight tubular pillarplex pore, paving the way to future mechanically interlocked molecules and materials. [ABSTRACT FROM AUTHOR]

The regularized and restored semilocal meta-generalized gradient approximation (meta-GGA) exchange–correlation functional r2SCAN [Furness et al., J. Phys. Chem. Lett. 11, 8208–8215 (2020)] is used to create three global hybrid functionals with varying admixtures of Hartree–Fock "exact" exchange (HFX). The resulting functionals r2SCANh (10% HFX), r2SCAN0 (25% HFX), and r2SCAN50 (50% HFX) are combined with the semi-classical D4 London dispersion correction. The new functionals are assessed for the calculation of molecular geometries, main-group, and metalorganic thermochemistry at 26 comprehensive benchmark sets. These include the extensive GMTKN55 database, ROST61, and IONPI19 sets. It is shown that a moderate admixture of HFX leads to relative improvements of the mean absolute deviations for thermochemistry of 11% (r2SCANh-D4), 16% (r2SCAN0-D4), and 1% (r2SCAN50-D4) compared to the parental semi-local meta-GGA. For organometallic reaction energies and barriers, r2SCAN0-D4 yields an even larger mean improvement of 35%. The computation of structural parameters (geometry optimization) does not systematically profit from the HFX admixture. Overall, the best variant r2SCAN0-D4 performs well for both main-group and organometallic thermochemistry and is better or on par with well-established global hybrid functionals, such as PW6B95-D4 or PBE0-D4. Regarding systems prone to self-interaction errors (SIE4x4), r2SCAN0-D4 shows reasonable performance, reaching the quality of the range-separated ωB97X-V functional. Accordingly, r2SCAN0-D4 in combination with a sufficiently converged basis set [def2-QZVP(P)] represents a robust and reliable choice for general use in the calculation of thermochemical properties of both main-group and organometallic chemistry. [ABSTRACT FROM AUTHOR]

The synthesis of heterogeneous Ti(IV)-based catalysts for ethylene polymerization following surface organometallic chemistry concepts is described. The unique feature of this catalyst arises from the silica support, KCC-1700. It has (i) a 3D fibrous morphology that is essential to improve the diffusion of the reactants, and (ii) an aluminum-bound hydroxyl group, [(≡Si–O–Si≡)(≡Si–O–)2Al–OH] 2, used as an anchoring site. The [(≡Si–O–Si≡)(≡Si–O–)(Al–O–)TiNp3] 3 catalyst was obtained by reacting 2 with a tetrakis-(neopentyl) titanium TiNp4. The structure of 3 was fully characterized by FT-IR, advanced solid-state NMR spectroscopy [1H, 13C], elemental and gas-phase analysis (ICP-OES and CHNS analysis), and XPS. The benefits of combining these morphological (3D structure) and electronic properties of the support (aluminum plus titanium) were evidenced in ethylene polymerization. The results show a remarkable enhancement in the catalytic performance with the formation of HDPE. Notably, the resulting HDPE displays a molecular weight of 3 200 000 g mol−1 associated with a polydispersity index (PD) of 2.3. Moreover, the effect of the mesostructure (2D vs. 3D) was demonstrated in the catalytic activity for ethylene polymerization. [ABSTRACT FROM AUTHOR]

Metal phosphates are important catalysts and materials in synthesis chemistry. Herein, we describe the synthesis and characterization of phosphate‐catecholate chelated Nd(III), Zr(IV) and Al(III) chlorides (2–5). These species are achieved via ethyl chloride elimination reaction of oxophosphoranes with corresponding metal chlorides. The product 2–5 represent a new serial of monometallic and bimetallic phosphate‐catecholate chelated metal complexes stabilized by both P−O and catecholate‐O donors. These findings pave the way for future explorations of such species in catalysis. [ABSTRACT FROM AUTHOR]

π‐Allyl complexes of transition metals are key species in organometallic chemistry and homogeneous catalysis. Palladium(II) π‐allyl complexes in particular, have gained a lot of attention, but their isoelectronic gold(III) counterparts long remained elusive. However, this situation changed during the last few years. This concept article describes the preparative routes, characterization, structure and reactivity of such species, together with their catalytic applications. The influence of the ancillary ligand at gold, either (P,C)/(N,C)‐cyclometalated or (P,N)‐hemilabile, is analysed in detail. The Au(III) and Pd(II) π‐allyl complexes are also compared to highlight the similarities and differences. [ABSTRACT FROM AUTHOR]

Numerous synthetic models of the FeMo‐co cluster of nitrogenases have been proposed to find the simplest structure with relevant reactivity. Indeed, such structures are able to perform multi‐electrons reduction processes, such as the conversion of N2 to ammonia, and of CO2 into methane and alkenes. The most challenging parameter to imitate is indeed the central carbide ligand, which is believed to maintain the integrity of iron sulfide assembly during the course of catalytic cycles. The study proposes the use of bis(diphenylthiophosphinoyl)methanediide (SCS)2− as an ideal platform for the synthesis of bi‐ and tetra‐metallic iron complexes, in which the iron‐carbon interaction is maintained upon structural diversification and redox state changes. [ABSTRACT FROM AUTHOR]

N-heterocyclic carbenes (NHCs) have emerged as a major direction in ancillary ligand development for stabilization of reactive metal centers in inorganic and organometallic chemistry. In particular, wingtipflexible NHCs have attracted significant attention due to their unique ability to provide a stericallydemanding environment for transition metals in various oxidation states. Herein, we report a new class of sterically-hindered, wingtip-flexible NHC ligands that feature N,C-chelating oxazole donors. These ligands are readily accessible through a modular arylation of oxazole derivatives. We report their synthesis and complete structural and electronic characterization. The evaluation of steric, electron-donating and p-accepting properties and coordination chemistry to Ag(I), Pd(II) and Rh(I) is described. Preliminary studies of catalytic activity in Ag, Pd and Rh-catalyzed coupling and hydrosilylation reactions are presented. This study establishes the fluxional behavior of a freely-rotatable oxazole unit, wherein the oxazolyl ring adjusts to the steric and electronic environment of the metal center. Considering the tremendous impact of sterically-hindered NHCs and their potential to stabilize reactive metals by N-chelation, we expect that this class of NHC ligands will be of broad interest in inorganic and organometallic chemistry. [ABSTRACT FROM AUTHOR]

Metal carbonyl complexes possess among the most storied histories of any compound class in organometallic chemistry. Nonetheless, these old dogs continue to be taught new tricks. In this Feature, we review the historic discoveries and recent advances in cleaving robust bonds (e.g., C–H, C–O, C–F) using carbonyl complexes of three metals: Mn, Fe, and Co. The use of Mn, Fe, and Co carbonyl catalysts in controlling selectivity during hydrofunctionalization reactions is also discussed. The chemistry of these earth-abundant metals in the field of robust bond functionalization is particularly relevant in the context of sustainability. We expect that an up-to-date perspective on these seemingly simple organometallic species will emphasize the wellspring of reactivity that continues to be available for discovery. [ABSTRACT FROM AUTHOR]

We introduce in this work a unique parameter for the quantitative assessment of the intrinsic strength of the π interaction between two monomers forming a complex. The new parameter is a local intermonomer stretching force constant, based on the local mode theory, originally developed by Konkoli and Cremer, and derived from the set of nine possible intermonomer normal vibrational modes. The new local force constant was applied to a diverse set of more than 70 molecular complexes, which was divided into four groups. Group 1 includes atoms, ions, and small molecules interacting with benzene and substituted benzenes. Group 2 includes transition metal hydrides and oxides interacting with benzene while Group 3 involves ferrocenes, chromocenes, and titanium sandwich compounds. Group 4 presents an extension to oxygen π–hole interactions in comparison with in-plane hydrogen bonding. We found that the strength of the π interactions in these diverse molecular complexes can vary from weak interactions with predominantly electrostatic character, found, e.g., for argon–benzene complexes, to strong interactions with a substantial covalent nature, found, e.g., for ferrocenes; all being seamlessly described and compared with the new intermonomer local mode force constant, which also outperforms other descriptors such as an averaged force constant or a force constant guided by the electron density bond paths. We hope that our findings will inspire the community to apply the new parameter also to other intermonomer π interactions, enriching in this way the broad field of organometallic chemistry with a new efficient assessment tool. [ABSTRACT FROM AUTHOR]

Bent (hetero)allenes such as carbodicarbenes and carbodiphosphoranes can act as neutral C‐donor ligands, and diverse applications in coordination chemistry have been reported. N‐Heterocyclic diazoolefins are heterocumulenes, which can function in a similar fashion as L‐type ligands. Herein, we describe the synthesis and the reactivity of an anionic diazoolefin. This compound displays distinct reactivity compared to neutral diazoolefins, as evidenced by the preparation of diazo compounds via protonation, alkylation, or silylation. The anionic diazoolefin can be employed as an ambidentate, X‐type ligand in salt metathesis reactions with metal halide complexes. Extrusion of dinitrogen was observed in a reaction with PCl(NiPr2)2, resulting in a stable phosphinocarbene. [ABSTRACT FROM AUTHOR]

Bent (hetero)allenes such as carbodicarbenes and carbodiphosphoranes can act as neutral C‐donor ligands, and diverse applications in coordination chemistry have been reported. N‐Heterocyclic diazoolefins are heterocumulenes, which can function in a similar fashion as L‐type ligands. Herein, we describe the synthesis and the reactivity of an anionic diazoolefin. This compound displays distinct reactivity compared to neutral diazoolefins, as evidenced by the preparation of diazo compounds via protonation, alkylation, or silylation. The anionic diazoolefin can be employed as an ambidentate, X‐type ligand in salt metathesis reactions with metal halide complexes. Extrusion of dinitrogen was observed in a reaction with PCl(NiPr2)2, resulting in a stable phosphinocarbene. [ABSTRACT FROM AUTHOR]

Complexes of metal atoms with organic molecules represent a broad variety of systems with many important applications, e.g., in metal–organic interfaces and organometallic chemistry. One class involves aromatic species like benzene (Bz). Here, such complexes with second-group metals are investigated systematically in terms of structure and shape, stability and isomerization, charge distribution and aromaticity, and polarity and IR spectra. Three groups of isomers are identified, varying from metastable to stable ones, in effect featuring "physisorption" or "chemisorption". In particular, the high polarity of binary complexes and nonadditive stabilization of ternary systems for some isomers are found. Also, the Bz component's shape alteration for different isomers and system sizes and related aromaticity variations are predicted to be considerable. Property evolution for the series of metal components is analyzed. [ABSTRACT FROM AUTHOR]