Organometallic Research Articles

Friedel–Crafts Reactivity with Sulfondiimidoyl Fluorides for the Synthesis of Heteroaryl Sulfondiimines

AbstractSulfur functional groups are ubiquitous in molecules used in the pharmaceutical and agrochemical industries, and within these collections sulfones hold a prominent position. The double aza‐analogues of sulfones, sulfondiimines, offer significant potential in discovery chemistry but to date their applications have been limited by the lack of convenient synthetic routes. The existing methods mainly rely on imination of low‐valent‐sulfur intermediates, or the combination of pre‐formed organometallic reagents and electrophilic S(VI)‐functionalities. Herein, we describe a Friedel–Crafts‐type reaction of sulfondiimidoyl fluorides with (hetero)aryls. This new SuFEx reactivity benefits from broad functional group tolerance, mild reaction conditions, and does not require the use of pre‐formed organometallic reagents. The efficient use of unprotected indoles and pyrroles, as well as furan, thiophene and carbocyclic aromatics, further demonstrates the advantages of these reactions. We show that the reactivity of the sulfondiimidoyl fluorides can be tuned by switching the N‐substituents, allowing an expansion of the range of coupling partners. The utility of the transformation is exemplified by the synthesis of the sulfondiimine analogue of the HIV‐I reverse transcriptase‐inhibitor L‐737,126.

Nanometer-thick TiO2 channel thin film transistors as radical monitors for plasma enhanced atomic layer deposition

Nanometer-thick-TiO2-channel thin-film transistors (TFTs) are examined as oxidizing-agent monitors for room-temperature atomic layer deposition (RTALD). RTALD is a plasma-based process using plasma-excited humidified argon where OH radicals oxidize the precursor-gas adsorbed surface. In the TFT, the anatase TiO2 channel, with a thickness of 16 nm, is attached to a 300 nm thick gate capacitor of SiO2, while the channel surface is exposed to the ALD ambient. A heavily doped n-type Si substrate attached to the gate SiO2 is used as the gate electrode. The gate width and length are 1000 and 60 μm, respectively. When the TFT is installed in the RTALD chamber, the drain-current waveform is recorded in the course of the metal organic gas adsorption, evacuation of the residual gas, oxidization, and evacuation. In the present study, three kinds of metal organic (MO) precursors, tetrakis(dimethyl)amino titanium, tris(dimethyl)amino silane, and trimethyl aluminum are examined. The drain current exhibits strong responses upon the exposure of the plasma excited humidified argon. This suggests that OH radicals in the plasma might oxidize the adsorbed MO precursors to produce the OH moieties, where the surface polarization of OH moieties might enhance channel conductivity. The experimental results suggest the applicability of the present TFT as a plasma monitor in RTALD.

Versatile Organometallic Synthesis of 0D/2D Metal@Germanane Nanoarchitectonics for Electrochemical Energy Conversion Applications.

Hydrogen-terminated 2D-Germanane (2D-GeH), a germanium-based 2D material akin to graphene, is receiving enormous attention owing to its predicted optoelectronic characteristics. However, experimental research of 2D-GeH is still in an early stage, and therefore its real implementation for task-specific applications will depend on the correct development of suitable chemical functionalization methods. Herein, a general and straightforward organometallic (OM) approach is provided for the robust functionalization of 2D-GeH with different 0D noble metal nanoparticles (M-NPs), resulting in 0D/2D M@GeH nanoarchitectonics. As a proof-of-principle, 0D/2D Pt@GeH and Au@GeH nanoarchitectonics have been successfully synthesized, characterized, and explored as unconventional electrocatalysts for boosting energy conversion reactions. While the hydrogen evolution reaction activity was evaluated for Pt@GeH, the oxygen reduction reaction was interrogated for Au@GeH. Interestingly, the implanted catalytic features of M-NPs yielded to 0D/2D M@GeH nanoarchitectonics with enhanced energy conversion activity comparing to pristine 2D-GeH counterpart. This work proves the suitability of 2D-GeH as unconventional substrates to stabilize nobleM-NPs, and the versatility of the OM approach for the custom design of a new family of 0D/2D M@GeH nanoarchitectonics to expand the implementation of monoelemental 2D materials as promising electrocatalysts in energy conversion field and beyond.

Tetratellura[36]octaphyrin(1.1.1.1.1.1.1.1) Metalation: From Dynamic Behavior to Rigid Chiral Figure-of-Eight Molecule; Activation of the C-Te Bond by Ruthenium.

The large expanded telluraporphyrin, tetratellura[36]octaphyrin(1.1.1.1.1.1.1.1), was synthesized in 7% yield by acid-catalyzed condensation of pyrrole with 2,5-bis(phenylhydroxymethyl)tellurophene and subsequent oxidation. The macrocycle acquires the chiral figure-eight conformation with two alternative spatial arrangements of the heterocyclic rings. The molecule exhibits dynamic behavior in solution, which was studied by means of 1H NMR spectroscopy. The reaction with chlorine led to a reversible oxidative addition at two distant tellurium atoms, which altered the preferred conformations. Metalation of the tetratellura[36]octaphyrin with triruthenium dodecacarbonyl selectively activated two of the eight Te-C bonds, resulting in the formation of an organometallic diruthenium compound. During the reaction, two tellurophene rings were converted to 1-ruthena-2-telluracyclohexadiene units containing octahedral ruthenium(II) centers. The rigid structure of this chiral complex allowed the separation of enantiomers.

Surface Coordination Chemistry of Graphitic Carbon Nitride from Ag Molecular Probes.

Graphitic carbon nitride (g-C3N4) has gained significant attention for its catalytic properties,especiallyin the development of Single Atom Catalysts (SACs).However,the surface chemistry underlying the formation of these isolated metal sites remains poorly understood.In thisstudyweemploy Surface OrganoMetallic Chemistry (SOMC) together with advanced microscopic and spectroscopic techniquesfor an in-depth analysis of functionalizedg-C3N4materials, where tailored organosilver probe molecules are used to monitor surface processes and characterize resulting surface species. Amulti-technique approach-including high-angle annular dark-field scanning transmission electron microscopy(HAADF-STEM), X-ray absorption spectroscopy (XAS), and multinuclear solid-state Nuclear Magnetic Resonance spectroscopy (ssNMR),coupled with density functional theory (DFT) calculations- identifies three primary surface speciesin Ag-functionalized g-C3N4:bis-NHC-Ag+, dispersed Ag+sites, andphysisorbed molecular precursor.These findings highlight a dynamic grafting process and provide insights into the surface coordination chemistryof functionalizedg-C3N4materials.

Electronic Structures of Late versus Early Transition Metal Imido Complexes from 15N‐NMR Signatures

AbstractImido ligand is a ubiquitous motif in organometallic chemistry, serving roles spanning from ancillary ligands to reactive sites. The nature of M=N bond is highly depended on the metal centres and their d‐electron configuration, with late transition metal (TM) imido complexes exhibiting contrasting features when compared to their early TM analogues. Envisioning to uncover general electronic descriptor for the nature of imido ligands, we computationally investigate the solid‐state 15N NMR signatures of late TM imido complexes with various central metals, geometries and d‐electron counts, and compare them against these of the corresponding early TM systems. The spectroscopic signatures are mostly driven by the presence of filled, π‐symmetry orbitals in late TM imido complexes, suggesting the development of high‐lying π(M=N) and low‐lying σ/σ*(M=N) orbitals. This contrasts with what is observed for the reported early TM systems, for which high‐lying σ‐type orbitals determine the NMR signature. Noteworthily, Ni‐ and Pd‐imido complexes with formal d10 configurations exhibit highly asymmetric nitrogen‐15 NMR signature with extremely deshielded principal components, because of the presence of filled, high‐lying antibonding π*(M=N) orbitals, consistent with their high reactivity. The sensitive response of 15N NMR signature to the nature of metal sites further highlights that chemical shift is a useful reactivity descriptor.

Early Days in the Hunt Laboratory at UVA, 1969-1980

Arriving at the University of Virginia in the autumn of 1969, Donald Hunt began his 50+ year career in academics with the study of organometallic chemistry, on which he had done his PhD thesis, and mass spectrometry, to which he was introduced while a postdoc in Klaus Biemann’s laboratory at the Massachusetts Institute of Technology. In the 1970s, Hunt’s lab pioneered the use of negative chemical ionization (CI) to enhance sensitivity for studying organic molecules, developed a system for simultaneously obtaining positive and negative CI spectra to augment structure elucidation, and built a prototype triple quadrupole instrument so effective at collisional dissociation that its commercial counterpart became the analytical instrument of choice for mixture analysis for the next decade and beyond. Foreseeing that the future lay in the analysis of biological molecules, by the end of the decade Hunt shifted his focus to peptides. The analysis of protein fragments had suddenly become more accessible thanks to the advent of the triple quadrupole and Barber’s invention of fast atom bombardment. As the ‘80s began and Hunt and his team sought to pursue larger and larger pieces of proteins, his attention turned to the development of mass spectrometers with greater mass range. While recounting their memories of these events, several of Hunt’s students and colleagues pay tribute to his support for them as individuals, as well as to his infectious enthusiasm for scientific endeavors that he so generously shared.

Cubosomes hydrogel containing silver based organometallic compounds for enhanced wound healing of burns: In vitro and in vivo studies

The aim of this study is to investigate the treatment of burn wounds and bacterial infections, specifically focusing on silver(I) N-heterocyclic carbene (Ag-NHC) loaded into cubosomes. Ag-NHC is an organometallic complex of silver (Ag) and can be considered an active pharmaceutical ingredient for the topical treatment of burns. A novel nanoparticle system, cubosome dispersions, was formulated using high pressure homogenization methods with different concentrations of lipid phase glyceryl monooleate (GMO), surfactants such as poloxamer 407 (F-127), and polyvinyl alcohol (PVA). The optimized formulation (U6) was characterized by in vitro drug release profile (90.54 ± 1.17 %), particle size (126.7 ± 0.98 nm), zeta potential (−21.6 ± 6.83 mV), entrapment efficiency (89.30 ± 1.46 %), and morphology as observed by transmission electron microscopy (TEM). The U6 formulation was incorporated into a hydrogel containing Carbopol 940 to form a cubosomal hydrogel (cubogel). The cubogel was characterized by the in vitro release of Ag-NHC (92 %), entrapment efficiency (>90 %), pH (5.3), viscosity (1.2 cP), spreadability, and TEM. From the in vitro drug release pattern, it was concluded that the U6 formulation showed slow and sustained drug release over 24 h, and demonstrated superior burn healing compared to marketed products. The in vivo wound healing study revealed that the cubogel demonstrated a superior burn healing rate compared to commercially available products (Quench® and Clotrimazole®). The in vivo histopathological results showed that the prepared cubogel was effective in treating second-degree burns, with no side effects or skin irritation, compared to commercial products. Additionally, Ag-NHC-loaded cubogel facilitated sustained release for treating burn wounds without any bacterial infections. The current findings provide a strong basis for the initiating phase 0 clinal trials, highlighting significant potential for the further research to benefit the pharmaceutical industry.

BODIPY Compounds Substituted on Boron.

BODIPY compounds are important organic dyes with exceptional spectral and photophysical properties and numerous applications in different scientific fields. Their widespread applications have flourished due to their easy structural modifications, which enable the preparation of different molecular structures with tunable spectral and photophysical properties. To date, researchers have mostly devoted their efforts to modifying BODIPY meso-position or pyrrole rings, whereas the substitution of fluorine atoms remains largely unexplored. However, chemistry of the boron atom is possible, and it enables tuning of the photophysical properties of the dyes, without tackling their spectral properties. Furthermore, modifications of boron affect the solubility and aggregation propensity of the molecules. This review article highlights methods for the preparation of 4-substituted compounds and the most important reactions on the boron of the BODIPY dyes. They were divided into reactions promoted by Lewis acid (AlCl3 or BCl3), or bases such as alkoxides and organometallic reagents. By using these two methodologies, it is possible to cleave B-F bonds and substitute them with B-C, B-N, or B-O bonds from different nucleophiles. A special emphasis in this review is given to still underdeveloped photochemical reactions of the boron atom of BODIPY dyes. These reactions have the potential to be used in the development of a new line of BODIPY photo-cleavable protective groups (also known as photocages) with bio-medicinal and photo-pharmacological applications, such as drug delivery.

The Chemistry of Levulinic Acid: Its Potential in the Production of Biomass‐based Chemicals

Biomass has been identified as the ultimate sustainable resource for all carbon‐based consumer products of the chemical industries in the future. Its catalytic conversion leads to the formation of various platform chemicals that could partially or even fully replace the fossil‐based building blocks that have been currently used in synthetic chemical processes. Among these compounds, levulinic acid (LA) has been recognized as a member of the "Top Value Added Chemicals from Biomass" and has attracted significant attention since the seminal paper reported by Werpy and Petersen in 2004. This review summarizes the properties, recent advances, and developments in the chemistry of levulinic acid. The production of LA from both plant and animal‐based carbohydrate feedstocks via 5‐hydroxymethylfurfural or furfuryl alcohol is discussed from a mechanistic perspective, highlighting intrinsic molecular‐level limitations to LA formation. The efficiencies of recently developed catalytic systems are also summarized and compared. Furthermore, the conversion of LA into high‐value‐added downstream chemicals, including its role in the synthesis of complex molecular structures, is overviewed. This section discussed the reactions of LA in the points of view of its various transformations on carbonyl‐, carboxy‐, methyl‐, and methylene functional groups. The reactions of these functionalities with C‐ ,N‐, O‐, and S‐nucleophiles, alcohols, amines, organometallic reagents, oxygen etc. were thematically summarized. Our review also outlooks to highlight the challenges and opportunities associated with the extensive research area of organic chemistry of levulinic acid.

Organometallic Compound Stabilizes All-Inorganic Tin-Based Perovskite Nanocrystals Against Antisolvent Post-Treatment.

The isolation and purification of all-inorganic Sn-based perovskite nanocrystals (PNCs) remain troublesome, as common antisolvents accelerate the collapse of the optically active perovskite structure. Here, we mitigate such instabilities and endow strong resistance to antisolvent by incorporating the organometallic compound zinc diethyldithiocarbamate, Zn(DDTC)2, during the solution-based synthesis of all-inorganic CsSnI3 nanocrystals. Thiourea is shown to form through the thermal-driven conversion of Zn(DDTC)2 during synthesis, which binds to un-passivated Sn sites on the crystal surface and shields it from irreversible oxidation reactions. The CsSnI3 PNCs capped with thiourea show great stability after two purification cycles using methyl acetate, with negligible change in morphology, phase, and optical properties. Moreover, the modified PNCs are resistant to other commonly used antisolvents, like ethyl acetate, 1-pentanol, and isopropanol, offering a platform to explore all-inorganic Sn-based nanocrystalline thin films and optoelectronics.

Enantioconvergent Cross‐Nucleophile Coupling: Copper‐Catalyzed Deborylative Cyanation

AbstractOrganoboron compounds are widely utilized in organic synthesis for their diverse reactivity, modular preparation, and stability compared to other classes of organometallic reagents. While organoboron species are commonly employed as nucleophiles in cross‐coupling reactions, their potential as racemic building blocks in enantioconvergent transformations remains largely untapped. Herein, we demonstrate the direct utilization of alkylboronic pinacol esters in intermolecular enantioconvergent transformations. Specifically, this work describes the development and mechanistic study of an enantioconvergent deborylative cyanation enabled by Cu catalysis. This method imparts a high degree of enantioselectivity and tolerates a wide range of common functional groups and heterocycles. The reaction is proposed to proceed through a radical‐relay mechanism. Aniline‐assisted homolysis of the carbon–boron bond results in prochiral alkyl radicals that are functionalized by in situ generated Cu(II)(CN)2 species in an enantioselective fashion. The Cu(II)(CN)2 intermediate was characterized by electron paramagnetic resonance (EPR) spectroscopy, and its electronic structure was probed using density functional theory (DFT) calculations. Computational studies were carried out to corroborate the proposed radical‐relay mechanism.

Monodentate Ligands in X-Cu(I)-Y Complexes—Structural Aspects

This structural study examines over 102 coordinate Cu(I) complexes with compositions such as C-Cu-Y (Y=HL, OL, NL, SL, SiL, BL, PL, Cl, Br, I, AlL, or SnL), N-Cu-Y (Y=OL, Cl), S-Cu-Y (Y=Cl, Br, I), P-Cu-Y (Y=Cl, I), and Se-Cu-Y (Y=Br, I). These complexes crystallize into three different crystal classes: monoclinic (seventy-two instances), triclinic (twenty-eight instances), and orthorhombic (eight instances). The Cu-L bond length increases with the covalent radius of the ligating atom. There are two possible geometries for coordination number two: linear and bent. A total of 21 varieties of inner coordination spheres exist, categorized into two hetero-types (C-Cu-Y, i.e., organometallic compounds and X-Cu-Y, i.e., coordination compounds). The structural parameters of hetero Cu(I) complexes were compared with trans-X-Cu (I)-X (homo) complexes and analyzed. The maximum deviations from linearity (180.0°) are, on average, 10.3° for Br-Cu(I)-Br, 16.6° for C-Cu(I)-Sn, and 35.5° for P-Cu(I)-I. These results indicate that ligand properties influence deviation from linearity, increasing in the order of hard < borderline < soft.

Synthesis and characterization of new organometallic lanthanides metal complexes for photodynamic therapy

New Schiff base ligand: 4-methoxy salicaldhyde-2-2-phenyl-hydrazono acetaldehíyde prepared by facile method. The molecular structures characterized by elemental analysis and proton magnetic resonance spectra (1H-NMR spectra). This spectra at the chemical shifts (3.5–10.39 ppm) confirmed the types and the numbers of protons. The sharp melting point at the range 110–112 °C confirmed purity. New optically active metal (samarium, terbium and gadolinium) complexes of the Schiff base synthesized in a one pot reaction. Vibrational IR spectra confirmed functional groups. Scanning electron microscopy micrographs confirmed that the modified microstructure of the metal complexes differed in morphology than the ligand. Powder X-ray diffraction patterns confirmed good crystalline structure. The optically activity of the solid metal complexes confirmed from electronic absorption spectra. The UV absorbance band at the wavelength range 280–390 nm and the intense phosphorescence bands up to 830 nm enabled application in photo dynamic therapy for apoptosis cancer cells by conversion triplet oxygen in the tissues into reactive singlet oxygen. Low charge transfer energy: 2.59–2.61 eV, high molar extinction coefficients (ε) at the order of magnitude \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\:{10}^{6}$$\\end{document} M− 1 cm− 1 and the intense phosphorescence bands reflected good photodynamic activity. The metal complexes are thermally stable.

Organometallic Chemistry Tools for Building Biologically Relevant Nanoscale Systems.

The recent emergence of organometallic chemistry for modification of biomolecular nanostructures has begun to rewrite the long-standing assumption among practitioners that small-molecule organometallics are fundamentally incompatible with biological systems. This Perspective sets out to clarify some of the existing misconceptions by focusing on the growing organometallic toolbox for biomolecular modification. Specifically, we highlight key organometallic transformations in constructing complex biologically relevant systems on the nanomolecular scale, and the organometallic synthesis of hybrid nanomaterials composed of classical nanomaterial components combined with biologically relevant species. As research progresses, many of the challenges associated with applying organometallic chemistry in this context are rapidly being reassessed. Looking to the future, the growing utility of organometallic transformations will likely make them more ubiquitous in the construction and modification of biomolecular nanostructures.

Remote Migratory Reductive Arylation of Unactivated Alkenes Enabled by Electrochemical Nickel Catalysis.

Transition metal-catalyzed cross-coupling reaction between organometallic reagents and electrophiles is a potent method for constructing C(sp2)-C(sp3) bonds. Given the characters of organometallic reagents, cross-reductive coupling is emerging as an alternative strategy. The resurgence of electrochemistry offers an ideal method for electrochemical reductive of cross-coupling electrophiles. Inspired by the mechanism of electrochemical metal hydride, our study proposed that Ni-H electrochemically catalyze the hydroarylation coupling of unactivated alkenes with aryl halides. 1,1-Diarylalkanes can be produced effectively. This method have advantages including mild conditions, excellent regioselectivity, and satisfactory yields.

Comparative determination of the time-dependent accumulation of metal oxides in the landfill gas combustion chamber deposits using SEM-EDS, XRF and ICP OES

Non-purified landfill gas (LFG) leads to the formation of complex deposits in combustion chambers due to impurities such as siloxanes, sulfur compounds, and organometallic compounds containing elements such as Si, S, Sb, Sn. This study focused on identifying the elemental composition of deposits from four combustion chambers using analytical techniques including SEM-EDS, WDXRF, and microwave digestion ICP OES. The dominant element, Si, with concentrations (wt%) in the deposits was measured by SEM-EDS, ICP-OES, and WDXRF, respectively, as follows: 17.04 ± 8.59, 21.89 ± 4.39, and 16.63 ± 0.94 for cylinder head deposits, and 13.28 ± 6.97, 15.40 ± 5.40, and 12.64 ± 1.64 for piston head deposits. Excluding C, O and N, which could not be analyzed by all three techniques, the multi-analytical approaches demonstrated strong correlations between EDS results and those obtained from WDXRF and ICP OES, with R2 values of 0.9173 and 0.9002 for cylinder head deposits, respectively. It was also revealed that the elemental composition of deposits varied between combustion chambers. The average mass fractions of all deposit surfaces were ranked as follows for elements exceeding 1 %: O (45.38 %) > Si (16.67 %) > Ca (9.87 %) > Sb (7.21 %) > S (5.98 %) > Sn (3.51 %) > C (2.83 %) > P (2.35 %). Elements below 1 % were ranked as: Na (0.91 %) > N (0.80 %) > Al (0.74 %) > Fe (0.48 %) > Mg (0.30 %). Consequently, the multi-spectrometry analysis approach provides a more comprehensive understanding of the deposit composition, enabling the determination of primary contributors and the most elements. Future studies may involve more general determining the concentrations of organometallic compounds in the LFG, which are the source of the elements found in the deposit.

Reductive C(sp2)–Si Cross‐Couplings by Catalytic Sodium‐Bromine Exchange

The metal‐halogen exchange reaction constitutes one of the most important preparative routes towards polar organometallic reagents such as aryllithium or Grignard reagents. However, despite extensive developments over the past eight decades, this fundamental organometallic elementary step has only been exploited stoichiometrically. Against this background, we demonstrate that the sodium‐bromine exchange reaction can be implemented in a catalytic setting as a mean to activate C(sp2)–Br bonds in a transition metal‐free manner en route to the regioselective and general preparation of (hetero)aryl silanes. Simply treating structurally diverse (hetero)aryl bromides with N‐tert‐butyl‐N’‐silyldiazenes (tBu–N=N–Si) as silylating reagents and inexpensive sodium alkoxides as catalytic promoters yields a range of aromatic organosilicon compounds under ambient conditions. Mechanistic studies provide solid evidence for the involvement of tert‐butyl sodium as the C(sp2)–Br metalating agent.

Nickel-Catalyzed Enantioselective Reductive Spirocyclization of 1,6-Enynes with o-Bromobenzaldehydes

We develop a Ni-catalyzed asymmetric reductive spirocyclization of 1,6-enynes with o-haloaryl aldehydes. This approach provides an efficient method for the construction of chiral spiroindanone pyrrolidine derivatives in good yields with excellent enantio- and diastereoselectivity (up to 99% ee, > 20/1 dr). This reaction does not require pre-prepared organometallic reagents and exhibits excellent substrate compatibility.

Reductive C(sp2)–Si Cross‐Couplings by Catalytic Sodium‐Bromine Exchange

The metal‐halogen exchange reaction constitutes one of the most important preparative routes towards polar organometallic reagents such as aryllithium or Grignard reagents. However, despite extensive developments over the past eight decades, this fundamental organometallic elementary step has only been exploited stoichiometrically. Against this background, we demonstrate that the sodium‐bromine exchange reaction can be implemented in a catalytic setting as a mean to activate C(sp2)–Br bonds in a transition metal‐free manner en route to the regioselective and general preparation of (hetero)aryl silanes. Simply treating structurally diverse (hetero)aryl bromides with N‐tert‐butyl‐N’‐silyldiazenes (tBu–N=N–Si) as silylating reagents and inexpensive sodium alkoxides as catalytic promoters yields a range of aromatic organosilicon compounds under ambient conditions. Mechanistic studies provide solid evidence for the involvement of tert‐butyl sodium as the C(sp2)–Br metalating agent.