Browse
Submit Data
Databases
API
Help

Dataset Information

15 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

From Imidazole toward Imidazolium Salts and N-Heterocyclic Carbene Ligands: Electronic and Geometrical Redistribution.

ABSTRACT: Investigations dealing with N-heterocyclic carbenes and their derivatives are usually centered on the influence that they exert by acting as catalysts, ionic liquids, or metallodrugs and consequently on their capabilities to tune the properties and reactivity of these systems. In this context, we aimed to focus on the internal molecular changes undergone by imidazole derivatives, from electronic and geometrical points of view. This work represents an empirical evidence of the molecular modifications that an imidazole skeleton undergoes upon protonation, alkylation, and metalation.

SUBMITTER: Velle A

PROVIDER: S-EPMC6641017 | biostudies-literature | 2017 Apr

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Publications

From Imidazole toward Imidazolium Salts and N-Heterocyclic Carbene Ligands: Electronic and Geometrical Redistribution.

Vellé Alba A Cebollada Andrea A Macías Ramón R Iglesias Manuel M Gil-Moles María M Sanz Miguel Pablo J PJ

ACS omega 20170410 4

Investigations dealing with N-heterocyclic carbenes and their derivatives are usually centered on the influence that they exert by acting as catalysts, ionic liquids, or metallodrugs and consequently on their capabilities to tune the properties and reactivity of these systems. In this context, we aimed to focus on the internal molecular changes undergone by imidazole derivatives, from electronic and geometrical points of view. This work represents an empirical evidence of the molecular modificat ...[more]

PMID: 31457511

Similar Datasets

Expedient syntheses of the N-heterocyclic carbene precursor imidazolium salts IPr.HCl, IMes.HCl and IXy.HCl.

Project description:The 1,3-diaryl-imidazolium chlorides IPr.HCl (aryl = 2,6-diisopropylphenyl), IMes.HCl (aryl = 2,4,6-trimethylphenyl) and IXy.HCl (aryl = 2,6-dimethylphenyl), precursors to widely used N-heterocyclic carbene (NHC) ligands and catalysts, were prepared in high yields (81%, 69% and 89%, respectively) by the reaction of 1,4-diaryl-1, 4-diazabutadienes, paraformaldehyde and chlorotrimethylsilane in dilute ethyl acetate solution. A reaction mechanism involving a 1,5-dipolar electrocyclization is proposed.

| S-EPMC2151073 | biostudies-literature

Shape-controllable formation of poly-imidazolium salts for stable palladium N-heterocyclic carbene polymers.

Project description:The imidazolium-based main-chain organic polymers are one of promising platforms in heterogeneous catalysis, the size and outer morphology of polymer particles are known to have important effects on their physical properties and catalytic applications, but main-chain ionic polymers usually generate amorphous or spherical particles. Herein, we presented a versatile and facile synthetic route for size- and shape-controllable synthesis of main-chain poly-imidazolium particles. The wire-shaped, spherical and ribbon-shaped morphologies of poly-imidazolium particles were readily synthesized through quaternization of bis-(imidazol-1-yl)methane and 2,4,6-tris(4-(bromomethyl)phenyl)-1,3,5-triazine, and the modification of their size and morphology were realized through adjusting solvent polarity, solubility, concentration and temperatures. The direct complexation of the particles with Pd(OAc)2 produced ionic polymers containing palladium N-heterocyclic carbene units (NHCs) with intactness of original morphologies. The particle morphologies have a significant effect on catalytic performances. Wire-shaped palladium-NHC polymer shows excellent catalytic activity and recyclabilty in heterogeneous Suzuki-Miyaura cross-coupling reaction.

| S-EPMC5381546 | biostudies-literature

Isolation of a C5-deprotonated imidazolium, a crystalline "abnormal" N-heterocyclic carbene.

Project description:The discovery two decades ago of metal-free stable carbenes, especially imidazol-2-ylidenes [N-heterocyclic carbenes (NHCs)], has led to numerous breakthroughs in organic and organometallic catalysis. More recently, a small range of complexes has been prepared in which alternative NHC isomers, namely imidazol-5-ylidenes (also termed abnormal NHCs or aNHCs, because the carbene center is no longer located between the two nitrogens), coordinate to a transition metal. Here we report the synthesis of a metal-free aNHC that is stable at room temperature, both in the solid state and in solution. Calculations show that the aNHC is more basic than its normal NHC isomer. Because the substituent at the carbon next to the carbene center is a nonbulky phenyl group, a variety of substitution patterns should be tolerated without precluding the isolation of the corresponding aNHC.

| S-EPMC2871154 | biostudies-literature

Methylpalladium complexes with pyrimidine-functionalized N-heterocyclic carbene ligands.

Project description:A series of methylpalladium(II) complexes with pyrimidine-NHC ligands carrying different aryl- and alkyl substituents R ([((pym)^(NHC-R))Pd(II)(CH3)X] with X = Cl, CF3COO, CH3) has been prepared by transmetalation reactions from the corresponding silver complexes and chloro(methyl)(cyclooctadiene)palladium(II). The dimethyl(1-(2-pyrimidyl)-3-(2,6-diisopropylphenyl)imidazolin-2-ylidene)palladium(II) complex was synthesized via the free carbene route. All complexes were fully characterized by standard methods and in three cases also by a solid state structure.

| S-EPMC4979653 | biostudies-literature

Stepwise Synthesis of Tetra-imidazolium Macrocycles and Their N-Heterocyclic Carbene Metal Complexes.

Project description:A modular stepwise synthetic method has been developed for the preperation of tetra-imidazolium macrocycles. Initially a series of three bis(imidazolylmethyl)benzene precursors were alkylated with 1,2-dibromoethane to produce the corresponding bis-bromoethylimidazolium bromide salts. In the second step the bis-bromoethylimidazolium bromide salts were reacted with selected bis(imidazolylmethyl)benzene molecules to produce a series of two symmetrical and three asymmetrical tetra-imidazolium macrocycles. These tetra-imidazolium salts act receptors for anions and 1H-NMR titration studies were used to determine the association constants between two of the macrocycles and the halide anions chloride, bromide and iodide. The tetra-imidazolium salts are precursors for N-heterocyclic carbene (NHC) ligands and the corresponding silver(I), gold(I), and palladium(II) NHC complexes have been prepared. Varied structures were obtained, which depend on the chosen macrocyclic ligand and metal ion and in the case of the coinage metals Ag(I) and Au(I), mono, di, and hexanuclear complexes were formed.

| S-EPMC6491846 | biostudies-literature

Carbenaporphyrins: No Longer Missing Ligands in N-Heterocyclic Carbene Chemistry.

Project description:The synthesis of an NHC-containing porphyrinoid ligand is presented. The formally antiaromatic 20??e- macrocyclic framework can be obtained via a 1,3-dipolar cycloaddition ("click-reaction") to form two triazole moieties which were alkylated to the respective triazolium macrocycle. Deprotonation of the ligand precursor with lithium bases to the respective dilithio carbenaporphyrin complex and transmetallation to scandium lead to complexes that exhibit orange fluorescence. Optical property combined with TD-DFT studies verify an aromatic character for each heterocyclic moiety rather than an antiaromatic macrocycle in the ligand precursor as well as in the complexes. While the geometric features of the carbenaporphyrin ligand strongly resemble those of porphyrin, DFT calculations reveal a stronger electron-donating ability of the new ligand.

| S-EPMC7898644 | biostudies-literature

Harnessing asymmetric N-heterocyclic carbene ligands to optimise SABRE hyperpolarisation.

Project description:The catalytic signal amplification by reversible exchange process has become widely used for the hyperpolarisation of small molecules to improve their magnetic resonance detectability. It harnesses the latent polarisation of parahydrogen, and involves the formation of a labile metal complex that often contains an N-heterocyclic carbene (NHC) ligand (e.g. [Ir(H)2(NHC)(pyridine)3]Cl), which act as a polarisation transfer catalyst. Unfortunately, if the target molecule is too bulky, binding to the catalyst is poor and the hyperpolarisation yield is therefore low. We illustrate here the behaviour of a series of asymmetric NHC containing catalysts towards 3,4- and 3,5-lutidine in order to show how catalyst design can be used to dramatically improve the outcome of this catalytic process for sterically encumbered ligands.

| S-EPMC6171487 | biostudies-literature

Influence of bulky yet flexible N-heterocyclic carbene ligands in gold catalysis.

Project description:Three new Au(I) complexes of the formula [Au(NHC)(NTf2)] (NHC = N-heterocyclic carbene) bearing bulky and flexible ligands have been synthesised. The ligands studied are IPent, IHept and INon which belong to the 'ITent' ('Tent' for 'tentacular') family of NHC derivatives. The effect of these ligands in gold-promoted transformations has been investigated.

| S-EPMC4661005 | biostudies-other

N-Heterocyclic carbene-catalyzed deaminative cross-coupling of aldehydes with Katritzky pyridinium salts.

Project description:By employing an N-heterocyclic carbene (NHC) catalyst, we developed a versatile catalytic system that enables deaminative cross-coupling reactions of aldehydes with redox-active pyridinium salts. Katritzky pyridinium salts behave as single-electron oxidants capable of generating alkyl radicals enabled by the redox properties of the enolate form of Breslow intermediates. The resultant alkyl radical undergoes efficient recombination with the NHC-bound aldehyde-derived carbonyl carbon radical for the formation of a C-C bond. The mild and transition metal-free reaction conditions tolerate a broad range of functional groups, and its utility has been further demonstrated by the modification of a series of peptide feedstocks and application to the three-component dicarbofunctionalization of olefins.

| S-EPMC8157273 | biostudies-literature

Anticancer Activity of Ag(I) N-Heterocyclic Carbene Complexes Derived from 4,5-Dichloro-1H-Imidazole.

Project description:A class of Ag(I) N-heterocyclic carbene silver complexes, 1-3, derived from 4,5-dichloro-1H-imidazole has been evaluated for their anticancer activity against the human cancer cell lines OVCAR-3 (ovarian), MB157 (breast), and Hela (cervical). Silver complexes 1-3 are active against the ovarian and breast cancer cell lines. A preliminary in vivo study shows 1 to be active against ovarian cancer in mice. The results obtained in these studies warrant further investigation of these compounds in vivo.

| S-EPMC2443426 | biostudies-literature

OmicsDI is part of the ELIXIR infrastructure

OmicsDI is an Elixir interoperability service. Learn more ›

OmicsDI Databases

PRIDE
PeptideAtlas
MassIVE
JPOST Repository
Physiome Model Repository

EGA
EVA
ENA
LINCS
PAXDB
Cell Collective

MetaboLights
Metabolomics Workbench
MetabolomeExpress
GNPS
BioModels
FAIRDOMHub

ArrayExpress
dbGaP
ExpressionAtlas
GEO
NODE

Information

Databases
Help
API
Contact us
Code on GitHub
Terms of use
Submit Data