Advances in the Synthesis and Applications of N-Heterocyclic Carbene Metal Complexes with a Focus on the Weak Base Route

Organometallics, Journal Year: 2023, Volume and Issue: 42(19), P. 2692 - 2730

Published: Sept. 21, 2023

N-heterocyclic carbene (NHC) ligands have evolved from being simple lab curiosities to tertiary phosphine mimics finally take center stage as unique supporting in organometallic chemistry, homogeneous catalysis, and more recently medicinal chemistry materials science applications. Some of these aspects are presented here a perspective researchers that been fascinated by the area for quite some time.

Language: Английский

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Recent advances of mesoionic N-heterocyclic olefins

Dalton Transactions, Journal Year: 2022, Volume and Issue: 51(24), P. 9191 - 9198

Published: Jan. 1, 2022

This Perspective article highlights the recent development of mesoionic N-heterocyclic olefins (mNHOs), where exo-cyclic olefinic carbon is not bonded to strongly electron-withdrawing groups. The unquenched basicity and nucleophilicity make mNHOs strong σ-donors enable unique reactivity patterns.

Language: Английский

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Visible-Light-Promoted Iridium(III)-Catalyzed Acceptorless Dehydrogenation of N-Heterocycles at Room Temperature

ACS Catalysis, Journal Year: 2022, Volume and Issue: 12(10), P. 6238 - 6245

Published: May 10, 2022

An effective visible-light-promoted iridium(III)-catalyzed hydrogen production from N-heterocycles is described. A single iridium complex constitutes the photocatalytic system playing a dual task, harvesting visible-light and facilitating C-H cleavage H2 formation at room temperature without additives. The presence of chelating C-N ligand combining mesoionic carbene along with an amido functionality in IrIII essential to attain transformation. Furthermore, also efficient catalyst for thermal reverse process under mild conditions, positioning itself as proficient candidate liquid organic carrier technologies (LOHCs). Mechanistic studies support light-induced Ir-H intermediate operating mode complex.

Language: Английский

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1,3‐Imidazole‐Based Mesoionic Carbenes and Anionic Dicarbenes: Pushing the Limit of Classical N‐Heterocyclic Carbenes

Angewandte Chemie International Edition, Journal Year: 2023, Volume and Issue: 62(36)

Published: May 3, 2023

Classical N-heterocyclic carbenes (NHCs) featuring the carbene center at C2-position of 1,3-imidazole framework (i.e. C2-carbenes) are well acknowledged as very versatile neutral ligands in molecular materials sciences. The efficiency and success NHCs diverse areas is essentially attributed to their persuasive stereoelectronics, particular potent σ-donor property. with unusual C4 (or C5) position, so-called abnormal (aNHCs) or mesoionic (iMICs), however superior σ-donors than C2-carbenes. Hence, iMICs have substantial potential sustainable synthesis catalysis. main obstacle this direction rather demanding synthetic accessibility iMICs. aim review article highlight recent advances, particularly by author's research group, accessing stable iMICs, quantifying properties, exploring applications In addition, viability use vicinal C4,C5-anionic dicarbenes (ADCs), also based on an framework, presented. As will be apparent following pages, ADCs hold potentials pushing limit classical enabling access conceptually new main-group heterocycles, radicals, catalysts, sets, more.

Language: Английский

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Application of first-row transition metal complexes bearing 1,2,3-triazolylidene ligands in catalysis and beyond

Chemical Society Reviews, Journal Year: 2024, Volume and Issue: 53(12), P. 6322 - 6344

Published: Jan. 1, 2024

Triazole-derived N-heterocyclic carbenes, available via click reactions, are versatile ligands for first-row transition metals, leading to complexes with attractive photochemical properties and catalytic activity, some defining the state-of-the-art.

Language: Английский

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Investigation of Huisgen's Noble metal catalyst click reaction mechanism for the synthesis of 1,4-disubstituted 1,2,3-triazoles

Molecular Catalysis, Journal Year: 2024, Volume and Issue: 566, P. 114412 - 114412

Published: Aug. 2, 2024

Language: Английский

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Electronic Coupling in 1,2,3-Triazole Bridged Ferrocenes and Its Impact on Reactive Oxygen Species Generation and Deleterious Activity in Cancer Cells

Inorganic Chemistry, Journal Year: 2022, Volume and Issue: 61(25), P. 9650 - 9666

Published: June 14, 2022

Mixed-valence (MV) binuclear ferrocenyl compounds have long been studied as models for testing theories of electron transfer and in attempts to design molecular-scale electronic devices (e.g., molecular wires). In contrary that, far less attention has paid MV ferrocenes anticancer agents. Herein, we discuss the synthesis six 1,2,3-triazole combined (spectro)electrochemical, paramagnetic resonance (EPR), computational, activity studies. Our synthetic approach was based on copper-catalyzed 1,3-dipolar azide–alkyne cycloaddition reaction enabled us obtain one step bearing either one, two, or three entities linked common core. Thus, two series complexes were obtained, which pertain derivatives 3′-azido-3′-deoxythymidine (AZT) 3-azidopropionylferrocene, respectively. Based experimental theoretical data, mono-oxidized species corresponding AZT trinuclear 3-azidopropionylferrocene categorized class II mixed-valence according classification proposed by Robin Day. Of importance is observation that these are more active against human A549 H1975 non-small-cell lung cancer cells than their congeners, do not show characteristics. Moreover, competes surpasses, dependent cell line, reference drugs such cisplatin, tamoxifen, 5-fluorouracil. The most from entire thymidine derivative with lowest IC50 value 5 ± 2 μM cells. major mechanism antiproliferative investigated reactive oxygen generation This hypothesis substantiated EPR spin-trapping experiments decreased presence N-acetyl cysteine (NAC) free-radical scavenger.

Language: Английский

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Pushing the Upper Limit of Nucleophilicity Scales by Mesoionic N‐Heterocyclic Olefins

Angewandte Chemie International Edition, Journal Year: 2023, Volume and Issue: 62(40)

Published: Aug. 4, 2023

A series of mesoionic, 1,2,3-triazole-derived N-heterocyclic olefins (mNHOs), which have an extraordinarily electron-rich exocyclic CC-double bond, was synthesized and spectroscopically characterized, in selected cases by X-ray crystallography. The kinetics their reactions with arylidene malonates, ArCH=C(CO2 Et)2 , gave zwitterionic adducts, were investigated photometrically THF at 20 °C. resulting second-order rate constants k2 (20 °C) correlate linearly the reported electrophilicity parameters E malonates (reference electrophiles), thus providing nucleophile-specific N sN mNHOs according to correlation lg °C)=sN (N+E). With 21

Language: Английский

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Palladium, iridium, and rhodium complexes bearing chiral N‐heterocyclic carbene ligands applied in asymmetric catalysis

Applied Organometallic Chemistry, Journal Year: 2022, Volume and Issue: 38(6)

Published: June 23, 2022

The field of asymmetric catalysis is rapidly developing and the chiral ligands play a key role in enantioselective transition‐metal catalysis. electron‐rich N ‐heterocyclic carbenes (NHCs) have established themselves as popular class stereodirecting ancillary to catalyze organic transformations more efficient ways. Several novel complexes combination with tailored ligand design emerged during last few decades tailor‐made NHCs can easily be accessed due modular synthesis their parent azolium salt precursors. Their donor capability molecular shape tuned by changing substituent at N‐atom or cyclic backbone framework. This review article aims describe recent advances this evolving research area using well‐defined possessing NHC ligands.

Language: Английский

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Mesoionic Imines (MIIs): Strong Donors and Versatile Ligands for Transition Metals and Main Group Substrates

Angewandte Chemie International Edition, Journal Year: 2022, Volume and Issue: 61(25)

Published: March 14, 2022

We report the synthesis and reactivity of 1,2,3-triazolin-5-imine type mesoionic imines (MIIs). The MIIs are accessible by a base-mediated cycloaddition between substituted acetonitrile an aromatic azide, methylation established routes subsequent deprotonation. C=O-stretching frequencies in MII-CO2 -Rh(CO)2 Cl complexes were used to determine overall donor strength. stronger donors than N-heterocyclic (NHIs). excellent ligands for main group elements transition metals which they display substituent-induced fluorine-specific interactions undergo C-H activation. DFT calculations gave insights into frontier orbitals MIIs. predict relatively small HOMO-LUMO gap compared other related ligands. potentially able act as both π-donor π-acceptor This highlights potential exciting properties with huge future development.

Language: Английский

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