Organometallic Research Articles

Ultra-high precision nano additive manufacturing of metal oxide semiconductors via multi-photon lithography

As a basic component of the versatile semiconductor devices, metal oxides play a critical role in modern electronic information industry. However, ultra-high precision nanopatterning of metal oxides often involves multi-step lithography and transfer process, which is time-consuming and costly. Here, we report a strategy, using metal-organic compounds as solid precursor photoresist for multi-photon lithography and post-sintering, to realize ultra-high precision additive manufacturing of metal oxides. As a result, we gain metal oxides including ZnO, CuO and ZrO2 with a critical dimension of 35 nm, which sets a benchmark for additive manufacturing of metal oxides. Besides, atomic doping can be easily accomplished by including the target element in precursor photoresist, and heterogeneous structures can also be created by multiple multi-photon lithography, allowing this strategy to accommodate the requirements of various semiconductor devices. For instance, we fabricate an ZnO photodetector by the proposed strategy.

Synthesis, Photophysical Properties, and Optical Limiting Behavior of Organometallic Complexes: Influence of Metal Centers and Conjugated Diimine Ligands

Four organometallic complexes featuring identical conjugated diimine ligands and varying transition metal centers (Rh(III), Ir(III), Ru(II), and Os(II)) were synthesized. A comprehensive investigation of the photophysical properties of these complexes and their corresponding diimine ligands was conducted by UV‐vis absorption, emission, and transient absorption (TA) spectroscopy, as well as optical power limiting (OPL) measurements. The incorporation of fluorene components with alkyl chains enhanced the π‐conjugation of the ligand, prevented intermolecular π‐π stacking, and improved complex solubility. The diimine ligands showed a slight solvation effect in their emission spectra, indicating that the main property of their emissive state was intramolecular charge transfer (CT). According to the valence states of the four complexes, they can be divided into two classes (Rh(III), Ir(III)) and (Ru(II), Os(II)). For TA spectrum, the former group exhibited positive ΔOD values across the 400‐800 nm range, while the latter showed large inverted peaks at 420‐500 nm due to significant ground‐state absorption in this wavelength range. Additionally, the optical limiting conduct of the complexes observed the order: 1d > 1a > 1c > 1b. Complex 1d exhibits powerful reverse saturable absorption (RSA) properties at 532 nm and could probably be used as an wonderful nonlinear absorbing material.

Electrochemistry of Nickelocene-Ferrocene Organometallic Complexes for Electrodeposition of Nickel–Iron–Based Nanostructured Film under Ambient Conditions for Oxygen Evolution Reaction

Electrochemistry of Nickelocene-Ferrocene Organometallic Complexes for Electrodeposition of Nickel–Iron–Based Nanostructured Film under Ambient Conditions for Oxygen Evolution Reaction

Nickel‐Catalyzed Reductive Protocol to Access Silacyclobutanes with Unprecedented Functional Group Tolerance

AbstractWhile significant progress has been made in the area of transition metal‐catalyzed ring‐opening and formal cycloaddition reactions of 1,1‐disubstituted silacyclobutanes (SCBs), synthesizing these SCBs—particularly those bearing additional functional groups—continues to present synthetic challenges. In this context, we present a novel Ni‐catalyzed reductive coupling reaction that combines 1‐chloro‐substituted silacyclobutanes with aryl or vinyl halides and pseudohalides, thereby obviating the need for organometallic reagents. This method facilitates the generation of 1,1‐disubstituted silacyclobutanes with a remarkable tolerance for various functional groups. This approach serves as a complementary and more step‐economical alternative to the commonly used yet moisture‐ and air‐sensitive nucleophilic substitution reactions involving Grignard or lithium reagents. Our initial mechanistic studies indicate that this reaction is initiated by oxidative cleavage of the Si−Cl bond in 1‐chlorosilacyclobutanes, which represents a distinct mechanism from the previously documented reductive coupling processes involving carbon electrophiles and chlorosilanes.

Nickel-Catalyzed Reductive Protocol to Access Silacyclobutanes with Unprecedented Functional Group Tolerance.

While significant progress has been made in the area of transition metal-catalyzed ring-opening and formal cycloaddition reactions of 1,1-disubstituted silacyclobutanes (SCBs), synthesizing these SCBs-particularly those bearing additional functional groups-continues to present synthetic challenges. In this context, we present a novel Ni-catalyzed reductive coupling reaction that combines 1-chloro-substituted silacyclobutanes with aryl or vinyl halides and pseudohalides, thereby obviating the need for organometallic reagents. This method facilitates the generation of 1,1-disubstituted silacyclobutanes with a remarkable tolerance for various functional groups. This approach serves as a complementary and more step-economical alternative to the commonly used yet moisture- and air-sensitive nucleophilic substitution reactions involving Grignard or lithium reagents. Our initial mechanistic studies indicate that this reaction is initiated by oxidative cleavage of the Si-Cl bond in 1-chlorosilacyclobutanes, which represents a distinct mechanism from the previously documented reductive coupling processes involving carbon electrophiles and chlorosilanes.

Facile Method to Obtain Functionalised η6-Bound Arenes in Ru(II) and Os(II) Half-Sandwich Complexes.

Half-sandwich Ru(II)- and Os(II)-arene complexes have great potential for catalytic and biological applications. The possibility of fine-tuning their chemical reactivity by including modifications in the ligands around the metal adds to their many advantages. However, structural modifications at the η6-bound arene have had significant synthetic limitations, particularly in the design of Os(II)-tethered complexes. For the first time, we have employed a practical C(sp3)-C(sp2) coupling to obtain 28 new Ru(II) and Os(II) η6-arene half-sandwich complexes with a wide variety of arene functionalities, including those that enable the formation of tether rings, such as quinoline, and coumarin. The introduction of novel functional groups at the arene in Ru(II)- and Os(II) half-sandwich complexes can broaden the synthetic scope of this type of organometallic complexes, and help to take full advantage of their structural diversity, for example, in intracellular catalysis.

Zirconium Phosphates and Phosphonates: Applications in Catalysis

This review covers recent advancements in the use of zirconium phosphates and phosphonates (ZrPs) as catalysts or catalyst supports for a variety of reactions, including biomass conversion, acid–base catalysis, hydrogenation, oxidation, and C-C coupling reactions, from 2015 to the present. The discussion emphasizes the intrinsic catalytic properties of ZrPs, focusing on how surface acidity, hydrophobic/hydrophilic balance, textural properties, and particle morphology influence their catalytic performance across various reactions. Additionally, this review thoroughly examines the use of ZrPs as supports for catalytic species, ranging from organometallic complexes and metal ions to noble metals and metal oxide nanoparticles. In these applications, ZrPs not only enhance the dispersion and stabilization of active catalytic species but also facilitate their recovery and reuse due to their robust immobilization on the solid support. This dual functionality underscores the importance of ZrPs in promoting efficient, selective, and sustainable catalytic processes, making them essential to the advancement of green chemistry.

Novel nanoliter spray enhanced microwave plasma ionization mass spectrometry for the simultaneous detection of heavy metals and organic plasticizers in soil: A case study in a lead-acid battery industrial park

Soil pollution is predominantly attributed to the presence of heavy metal elements and organic compounds; However, current detection methodologies are restricted to the identification of only one of these two sources at a time. A novel analytical approach, known as nanoliter spray enhanced microwave plasma ionization mass spectrometry (Nano-Spray-EMPI-MS), has been developed to facilitate the simultaneous detection of both heavy metals and organic pollutants in soil samples. This technique is characterized by its requirement for minimal sample volumes, thereby allowing for efficient and rapid analysis. The research concentrated on the simultaneous analysis of five heavy metals (Pb, Zn, Cu, Cr, and Ni) and three major phthalates (PAEs), specifically DEHP, DBP, and DMP. The detection and quantification limits for the heavy metals were established to be between 0.16-0.57 and 0.53–1.88 μg L−1, respectively, while the limits for the PAEs ranged from 0.02 to 0.05 and 0.07–0.16 μg L−1. Validation of the method's efficacy in soil detection demonstrated recovery rates of 90.9 %–105.7 % for heavy metals and 89.4 %–97.2 % for PAEs. The application of this method analyzing soil samples collected from an area adjacent to a lead-acid battery industrial park in China revealed varying levels of contamination by both heavy metals and PAEs. Notably, Lead contamination was found to be the most pronounced, with a peak concentration of 862.5 mg kg−1 and a correspondingly high pollution index. These findings are significant for evaluating local ecological risks, pinpointing sources of pollution, and formulating effective pollution management strategies in the region.

Stereochemical influence of 4ʹ-methyl substitutions on truncated 4ʹ-thioadenosine derivatives: Impact on A3 adenosine receptor binding and antagonism

Herein, we investigated the stereochemical effects of 4ʹ-methyl substitution on A3 adenosine receptor (A3AR) ligands by synthesizing and evaluating a series of truncated 4ʹ-thioadenosine derivatives featuring 4ʹ-α-methyl, 4ʹ-β-methyl, and 4ʹ,4ʹ-dimethyl substitutions. We successfully synthesized these derivatives, using the stereoselective addition of an organometallic reagent, KSAc-mediated sulfur cyclization, and Vorbrüggen condensation. Binding assays demonstrated that the 4ʹ-β-methyl substitution conferred the highest affinity for A3AR, with compound 1 h exhibiting a Ki = 3.5 nM, followed by the 4ʹ,4ʹ-dimethyl and 4ʹ-α-methyl substitutions. Notably, despite the absence of the 5ʹ-OH group, compound 1 h unexpectedly displayed partial agonism. Computational docking studies indicated that compound 1 h, the β-methyl derivative, adopted a South conformation and maintained strong interactions within the receptor, including a critical interaction with Thr94, a residue known to be notable for agonistic effects. Conversely, compound 2 h, the α-methyl derivative, also adopted a South conformation but resulted in a flattened structure that hindered interactions with Thr94 and Asn250. The dimethyl derivative 3 h exhibited steric clashes with Thr94, contributing to a reduction in binding affinity. However, the docking results for 3 h indicated a North conformation, suggesting that the change in sugar conformation due to the additional 4ʹ-methyl group altered the angle between the α-methyl group and the sugar plane, enabling binding despite the increased steric bulk. These findings suggest that not only do the substituents and their stereochemistry influence receptor–ligand interactions, but the conformation and the resulting spatial orientation of the substituents also play a crucial role in modulating receptor–ligand interaction. This stereochemical insight offers a valuable framework for the design of new, selective, and potent A3AR ligands, potentially facilitating the development of novel therapeutics for A3AR-related diseases such as glaucoma, inflammation, and cancer.

An Organometallic Erbium Bismuth Cluster Complex Comprising a Bi66- Zintl Ion.

An organometallic erbium bismuth cluster complex, [K(THF)4]2[Cp*2Er2Bi6] (1), featuring a heterometallocubane core was isolated. The cube emerges from the rare Bi66- Zintl ion, bridging two erbium centers for the first time. SQUID magnetometry and ab initio calculations uncovered dominant antiferromagnetic coupling enabled through the chair-like hexabismuth anion. The gained insight will promote the design of future polynuclear magnetic molecules comprising prolate lanthanide ions.

Amide Synthesis from Decarboxylative Coupling of Isocyanates and Carboxylic Acids.

Isocyanates are versatile electrophiles that can react with a wide range of nucleophiles to afford important organic structures. Although the reactions between isocyanates and alcohols, amines and organometallic reagents have been well established, the synthesis of amides through the decarboxylative condensation of carboxylic acids and isocyanates is less appreciated. In this review, the synthesis of isocyanates and its application on amide synthesis through the condensation with carboxylic acids are summarized and discussed. It is our hope that this review will attract more attention to this less mentioned transformation and inspire new developments in the fields of organic synthesis, polymer synthesis and chemical biology.

Antiaromatic 2-Azaboroles with π4σ2 Electronic Configuration.

Similar to pyridine, which is a structural analog of benzene, 2-azaborole can be viewed as a structural analog of borole, in which the CH group at the 2-position is replaced by an N atom. Due to its unique π4σ2 electronic configuration, it should exhibit Lewis acidity, antiaromaticity, as well as Lewis basicity simultaneously. However, this uniqueness also makes its synthesis and isolation particularly challenging. One anticipated issue is its readiness for self-dimerization. This work proposes 2-azaborole and targets the synthesis and characterization of its derivatives for the first time. By reacting benzoborirene C6H4{BN(SiMe3)2} with bulky nitriles, crystalline benzo-fused 2-azaboroles have been successfully achieved and fully characterized. The importance of steric hindrance has been experimentally verified, showing that insufficient kinetic protection results in the dimerization of benzo-fused 2-azaboroles to form BN-allenophanes, a class of 10-membered macrocyclic compounds featuring two BN-allene units. The unique electronic structure of 2-azaborole as well as the mechanism of dimerization has been corroborated by theoretical calculations. In addition, its ability to act both as a Lewis acid and a Lewis base is demonstrated through its reaction with 1,3-diisopropyl-4,5-dimethylimidazolin-2-ylidene (MeIiPr) and AlCl3, respectively, which also implies the potential of the 2-azaborole motif as a σ-donor ligand for main group and organometallic chemistry.

Ring-Opening Reactions of Imidazolidines and Hexahydropyrimidines with Grignard Reagents.

We herein report an unprecedented ring-opening of unstrained cyclic aminals such as imidazolidines and hexahydropyrimidines by the use of Grignard and cuprate reagents to give secondary sulfonamides bearing diversely substituted tertiary amines in the β- or γ-position. This synthetic procedure can be carried out in a one-pot fashion without collateral reactions that are commonly associated with sp3-organometallic multicomponent Mannich-type reactions, indicating the fundamental role of sulfonamide protection of the second nitrogen atom in the generation of the cyclic aminal and in the ring-opening process. Computational density functional theory (DFT) data point to the formation of a transient iminium ion intermediate, in which the Lewis acidity of the cationic component of the organometallic reagent triggers the ring-opening process by coordination. The presented method allows the nucleophilic decoration of diamines including those bearing an adjacent chiral center to the tertiary amine not easily achievable by means of alternative standard synthetic procedures.

Reversible Grafting in Surface Organometallic Chemistry with a Late Transition‐Metal Amidinate Precursor

Supported catalysts are central to industrial catalytic processes. While traditional synthesis methods often yield poorly defined materials, thus complicating structural elucidation, Surface Organometallic Chemistry (SOMC) offers a solution, producing well‐defined structures. Recent advances in SOMC precursor development have shown that amidinate‐based precursors are a privileged class of precursors to generate supported metallic nanoparticles. In that context, this study investigates the grafting mechanism of a prototypical amidinate precursor, Ir(COD)(DIA) (1‐Ir), onto SiO2. Unique to amidinate complexes, grafting is shown to occur without ligand release, creating a reversible covalent bond. Using Ir‐TBOS as a molecular analogue, the structure of the grafted species and the reversibility of the reaction with O‐H groups are demonstrated using IR spectroscopy, single X‐Ray diffraction, variable‐temperature NMR spectroscopy, X‐Ray absorption spectroscopy (XAS), and supported by DFT calculations. Notably, we show that a partial degrafting is also possible at elevated temperatures under vacuum

Sustainable Formate Production via Highly Active CO2 Hydrogenation Using Porous Organometallic Polymer with Ru-PNP Active Sites.

Efforts to combine the advantages of homogeneous catalysts in terms of activity with the ease of separation process offered by heterogeneous catalysts continue to be actively pursued in the field of catalyst development. Heterogeneous catalysts were synthesized from Ru-MACHO organometallic compounds, recognized for their high hydrogenation catalytic activity linked to the active site of the Ru-PNP motif, through direct polymerization utilizing the Friedel-Crafts reaction. These catalysts were then applied for the conversion of greenhouse gas carbon dioxide (CO2) into formate via hydrogenation, exhibited with a record-high turnover frequency of 31,700 and a productivity of 36,100 kgformate/(kgcatalyst·d). Furthermore, the facile separation characteristics and recyclability of the heterogeneous catalysts were confirmed.

Navigating Ball Mill Specifications for Theory-to-Practice Reproducibility in Mechanochemistry.

The rising prospects of mechanochemically assisted syntheses hold promise for both academia and industry, yet they face challenges in understanding and, therefore, anticipating respective reaction kinetics. Particularly, dependencies based on variations in milling equipment remain little understood and globally overlooked. This study aims to address this issue by identifying critical parameters through kinematic models, facilitating the reproducibility of mechanochemical reactions across the most prominent mills in laboratory settings, namely planetary and mixer mills. Through a series of selected experiments replicating major classes of organic, organometallic, transition metal-catalyzed, and inorganic reactions from literature, we rationalize the independence of kinematic parameters on reaction kinetics when the accumulated energy criterion is met. As a step forward and to facilitate the practicability of our findings, we provide a freely accessible online tool[†] that allows the calculation of respective energy parameters for different planetary and mixer mills. Our work advances the current understanding of mechanochemistry and lays the foundation for future rational exploration in this rapidly evolving field.

Navigating Ball Mill Specifications for Theory‐to‐Practice Reproducibility in Mechanochemistry

AbstractThe rising prospects of mechanochemically assisted syntheses hold promise for both academia and industry, yet they face challenges in understanding and, therefore, anticipating respective reaction kinetics. Particularly, dependencies based on variations in milling equipment remain little understood and globally overlooked. This study aims to address this issue by identifying critical parameters through kinematic models, facilitating the reproducibility of mechanochemical reactions across the most prominent mills in laboratory settings, namely planetary and mixer mills. Through a series of selected experiments replicating major classes of organic, organometallic, transition metal‐catalyzed, and inorganic reactions from literature, we rationalize the independence of kinematic parameters on reaction kinetics when the accumulated energy criterion is met. As a step forward and to facilitate the practicability of our findings, we provide a freely accessible online tool[†] that allows the calculation of respective energy parameters for different planetary and mixer mills. Our work advances the current understanding of mechanochemistry and lays the foundation for future rational exploration in this rapidly evolving field.

Spin Crossover and Its Application in Organometallic Catalysis: Concepts and Recent Progress.

Spin crossover is one of the most important properties of open-shell metal complexes. In organometallic catalytic reactions, catalysts can alter reaction kinetics by spin crossover, i.e., accelerating or hindering the reaction progression, as well as altering reaction pathways, modulating the reaction selectivity or promoting new reactions. This personal account outlines the introduction and development of important concepts such as "two-state reactivity" involving spin crossover, and proposes a new concept, "spin-responsive catalysis" to summarize the catalytic processes in which spin effects are present. Finally, the electronic mechanism of spin crossover accelerating the reaction and the role of spin crossover in changing the reaction path and regulating the reaction selectivity are introduced by taking two recent typical iron-catalyzed reactions recently reported by our group as examples.

Chiral Organometallic Complexes Derived from Helicenic N-Heterocyclic Carbenes (NHCs): Design, Structural Diversity, and Chiroptical and Photophysical Properties.

ConspectusRecently, helicene derivatives have emerged as an important class of molecules with potential applications spanning over asymmetric catalysis, biological activity, magnetism, spin filtering, solar cells, and polymer science. To harness their full potential, especially as emissive components in circularly polarized organic light-emitting diodes (CP-OLEDs), generating structural chemical diversity and understanding the resulting photophysical and chiroptical properties are crucial. In this Account, we shed light on chemical engineering combining helicene and N-heterocyclic carbene (NHC) chemistries to create transition-metal complexes with unique architectures and describe their photophysical and chiroptical attributes. The σ-donating and π-accepting capabilities of the helically chiral π-conjugated NHCs endow the complexes with remarkable structural and electronic features. These characteristics manifest in phenomena such as chirality induction, very long-lived phosphorescence, and strong chiroptical signatures (electronic circular dichroism and circularly polarized luminescence).We describe the different classes of ligands primarily developed in our group by classifying them according to their connection between the helicenic moiety and the imidazole precursor. This connection is essential in determining the degree of π-conjugation and characterizing the emissive state. We comprehensively discuss 6-coordinate, 4-coordinate, and 2-coordinate complexes, delving into their structural nuances and examining how the interplay between metals and auxiliary ligands shapes their photophysical properties, with interpretations enriched by DFT calculations. Helicenes are known to promote intersystem crossing thanks to strong spin-orbit coupling, while metals offer robust frameworks leading to a variety of molecular architectures with specific topologies together with distinct excited-state properties. The electronic configurations and energy levels of the ligand and metal orbitals thus significantly modulate the photophysical and chiroptical behaviors of these complexes. In-depth analysis of chiroptical properties, notably electronic circular dichroism and circularly polarized luminescence, emphasizes the influence of different stereogenic elements on the chiroptical responses across various energy ranges with appealing "match-mismatch" effects. Finally, we describe future prospects of helicene NHCs, particularly in the context of emerging research on cost-effective and abundant transition metals for materials science and for photocatalysis. Indeed, the inherent long-lived MLCT, excited-state delocalization, structural rigidity, and intrinsic chirality of these complexes present intriguing avenues for future investigations.

Potential of organometallic complexes in medicinal chemistry

Abstract Organometallic complexes, which include ligands such as carbon monoxide (CO), carbenes, alkyls, phenyls, p-bound alkynes, alkenes, cyclopentadienyls, and arenes, have been extensively utilized in fields like materials chemistry and catalysis. These complexes also offer opportunities for the development of new medications with unique modes of action. Specifically, we are interested in anticancer drugs that can enhance the effectiveness of platinum treatments, broaden their range of action, reduce adverse effects, and prevent resistance. The distinct physiochemical properties of organometallic complexes have made them valuable in homogeneous catalysis, including the production of lead compounds and therapeutic possibilities. Over the past 20 years, a small group of researchers worldwide has explored the medical applications of these compounds’ unique characteristics, such as their structural diversity, potential for ligand exchange, and redox and catalytic properties. The results have been remarkable, and it is anticipated that numerous other organometallic compounds will undergo clinical trials in the coming years in addition to those already underway. In this brief study, we outline the advantages that organometallic metal complexes have over coordination compounds and pure organic molecules.