Smart N-Heterocyclic Carbene Ligands in Catalysis

Chemical Reviews, Journal Year: 2017, Volume and Issue: 118(19), P. 9988 - 10031

Published: Feb. 2, 2017

It is well-recognized that N-heterocyclic carbene (NHC) ligands have provided a new dimension to the design of homogeneous catalysts. Part success this type resides in limitless access variety topologies with tuned electronic properties, but also ability family NHCs are able adapt their properties specific requirements individual catalytic transformations. The term "smart" used here refer switchable, multifunctional, adaptable, or tunable and, general, all those modify steric fulfill defined reaction. purpose review comprehensively describe types smart NHC by focusing attention on catalytically relevant ligand-based reactivity.

Language: Английский

---

Metal complexes with oxygen-functionalized NHC ligands: synthesis and applications

Chemical Society Reviews, Journal Year: 2017, Volume and Issue: 46(3), P. 632 - 733

Published: Jan. 1, 2017

Hybrid NHC ligands and complexes in which an oxygen-donor type functionality is associated with the carbene donor are surveyed.

Language: Английский

---

Borrowing Hydrogen Amination Reactions: A Complex Analysis of Trends and Correlations of the Various Reaction Parameters

ACS Catalysis, Journal Year: 2022, Volume and Issue: 12(12), P. 7142 - 7198

Published: June 1, 2022

Borrowing hydrogen or the autotransfer amination is a powerful approach to create single C–N bonds, starting from stable and readily available substrates: amines alcohols. It considered as one of most atom-efficient green methods synthesize complex amines. Herein, we attempted arrange array existing data in comprehensive structured manner determine correlations between experimental conditions catalysis outcome both within different groups catalysts defined using machine analysis. For each type N-nucleophiles (aromatic, aliphatic, heteroaromatic amines, amides), efficient working were suggested, including attributing optimal base temperature regime for metal.

Language: Английский

---

A leap forward in iridium–NHC catalysis: new horizons and mechanistic insights

Chemical Society Reviews, Journal Year: 2018, Volume and Issue: 47(8), P. 2772 - 2808

Published: Jan. 1, 2018

Ir–NHC catalysts have been crucial to the advance of an ever-growing diversity processes thanks their prolific reactivity and mechanistic flexibility.

Language: Английский

---

Ruthenium(II) Complexes of Heteroditopic N-Heterocyclic Carbene Ligands: Efficient Catalysts for C–N Bond Formation via a Hydrogen-Borrowing Strategy under Solvent-Free Conditions

Inorganic Chemistry, Journal Year: 2020, Volume and Issue: 59(3), P. 1835 - 1847

Published: Jan. 13, 2020

Both imidazol-2-ylidene (ImNHC) and 1,2,3-triazol-5-ylidene (tzNHC) have evolved to be elite groups of N-heterocyclic carbene (NHC) ligands for homogeneous catalysis. To develop efficient ruthenium(II)-based catalysts incorporating these C-N bond-forming reactions via hydrogen-borrowing methodology, we utilized chelating integrated with ImNHC mesoionic tzNHC donors connected a CH2 spacer diverse triazole backbone. The synthesized ruthenium(II) complexes 3 are found highly bond formation across wide range primary amine alcohol substrates under solvent-free conditions, among all the studied here, catalyst 3a mesityl substituent displayed maximum activity. our delight, is also effective selective mono-N-methylation various anilines utilizing methanol as coupling partner, known relatively more difficult than other alcohols. Furthermore, complex delivers substituted quinolines successfully reaction 2-aminobenzyl several secondary Importantly, exhibited highest activity reported both N-benzylation aniline [achieving turnover number (TON) 50000] realization quinoline 8a by reacting 2-phenylethanol (attaining TON 30000).

Language: Английский

---

Transfer Hydrogenation from Glycerol: Activity and Recyclability of Iridium and Ruthenium Sulfonate-Functionalized N-Heterocyclic Carbene Catalysts

ACS Sustainable Chemistry & Engineering, Journal Year: 2017, Volume and Issue: 5(5), P. 3963 - 3972

Published: March 27, 2017

Three ruthenium(II) and two iridium(III) N-heterocyclic carbene (NHC) complexes functionalized with sulfonates are compared respect to their activity selectivity for the transfer hydrogenation of imines, aldehydes, ketones, olefins using neat glycerol as hydrogen donor solvent. Four five catalysts likely proceed through a monohydride mechanism more active imines than olefins. The fifth catalyst proceeds dihydride is found be carbonyls Lactic acid observed only detectable byproduct from glycerol. Quantitative poisoning experiments 1,10-phenanthroline suggest that predominant catalytically species ligated homogeneous complex weak binding poison. potential recycling explored: ruthenium NHC chelating ligands robust recyclable relative iridium mono-NHC catalyst. reason traced rate degradation in presence KOH but no substrate. This when used, replacing isopropanol allows fully recyclable.

Language: Английский

---

Recent advances on N-heterocyclic carbene transition metal complexes for dehydrogenative catalysis using alcohols

Catalysis Today, Journal Year: 2020, Volume and Issue: 370, P. 114 - 141

Published: Oct. 20, 2020

Language: Английский

---

Synthesis and Derivatization of a Carbene‐Sulfinate Palladacycle

Applied Organometallic Chemistry, Journal Year: 2025, Volume and Issue: 39(3)

Published: Feb. 7, 2025

ABSTRACT An unprecedented C‐SO oxidative‐cleavage reaction was disclosed for fused thiazoline‐1‐oxide‐azolium salts with Ag 2 O to afford C carbene ^SO palladacyclic complexes. The complex could undergo reversible redox reactions Br an intermediary N‐heterocyclic (NHC) a sulfonyl bromide dangling group. This allowed divergent hydrolysis, alcoholysis, and aminolysis prepare series of sulfonate sulfonamide functionalized NHC complexes ^NSO palladacycle via further deprotonation. Selected were employed in catalysis show excellent activities the aqueous Suzuki‐Miyaura coupling hydroamination aryl alkynes.

Language: Английский

---

Molecular Engineering of Iridium Blue Emitters Using Aryl N‐Heterocyclic Carbene Ligands

European Journal of Inorganic Chemistry, Journal Year: 2016, Volume and Issue: 2016(32), P. 5089 - 5097

Published: Sept. 9, 2016

The synthesis of a new series neutral bis[2‐(2′,4′‐difluorophen‐2′‐yl)pyridine][1‐(2′‐aryl)‐3‐methylimidazol‐2‐ylidene]iridium(III) complexes is reported. Each complex has been characterized by NMR spectroscopy, UV/Vis spectrophotometry, and cyclic voltammetry, the photophysical properties examined in depth. Furthermore, two have single‐crystal X‐ray diffraction analysis. By systematically modifying cyclometalating aryl group on N‐heterocyclic carbene (NHC) ligand from 2,4‐dimethoxyphenyl to 6‐methoxy‐2‐methyl‐3‐pyridyl, energy levels Ir were modified produce blue emitters with increased HOMO triplet‐state energies. OLED devices fabricated these showed external quantum efficiencies (EQEs) range 2.3–3.2 % low turn‐on values 2.7–2.9 V efficacies up 6.3 %.

Language: Английский

---

Synthesis, Structure, Biological Evaluation, and Catalysis of Two Pyrazole‐Functionalized NHC–Ru^II Complexes

European Journal of Inorganic Chemistry, Journal Year: 2016, Volume and Issue: 2017(3), P. 616 - 622

Published: Nov. 4, 2016

Two ruthenium complexes, 3a and 3b , bearing pyrazole‐functionalized N‐heterocyclic carbenes (NHCs) were prepared, their structures characterized by X‐ray diffraction analysis. Given promising anticancer potential, we evaluated the cytotoxicity of both complexes against a panel human cancer cell lines, including breast Bcap‐37, colorectal LoVo, gastric SCG7901, cisplatin‐resistant SCG7901‐R cells. In vitro results showed that complex inhibited proliferation, which exhibited comparable to clinically approved cisplatin. More impressively, evoked significant rates death cells, displaying an approximately 13‐fold lower IC 50 value in this type than cisplatin (i.e., 5.8 ± 0.4 µ m vs. 83.1 14.5 ). addition, ruthenium–NHC demonstrated be efficient catalysts for oxidation various alcohols. By exploiting them as catalysts, variety carbonyl products obtained excellent yields. Collectively, these highlighted potential using highly well candidates treating cancers are resistant platinum‐based therapy.

Language: Английский

---