Experimental and Theoretical Approaches to the Influence of the Addition of Pyrene to a Series of Pd and Ni NHC‐Based Complexes: Catalytic Consequences

Valdés, Hugo; Poyatos, Macarena; Ujaque, Gregori; Peris, Eduardo

doi:10.1002/chem.201404618

Cited by 49 publications

(28 citation statements)

References 84 publications

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“…The trimetallic nature of the complex was further confirmed by mass spectrometry, which revealed a peak at m / z 810.7, assigned to [M − 2Cl] 2+ . Compound 4 is very interesting, because despite the fact that many [NiCpX(NHC)] complexes have already been reported [ 49 – 53 ], to our knowledge, this is the first tris-MIC-trinickel complex described so far.…”

Section: Resultsmentioning

confidence: 99%

Rhodium, iridium and nickel complexes with a 1,3,5-triphenylbenzene tris-MIC ligand. Study of the electronic properties and catalytic activities

Mejuto¹,

Royo²,

Guisado‐Barrios³

et al. 2015

Beilstein J. Org. Chem.

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SummaryThe coordination versatility of a 1,3,5-triphenylbenzene-tris-mesoionic carbene ligand is illustrated by the preparation of complexes with three different metals: rhodium, iridium and nickel. The rhodium and iridium complexes contained the [MCl(COD)] fragments, while the nickel compound contained [NiCpCl]. The preparation of the tris-MIC (MIC = mesoionic carbene) complex with three [IrCl(CO)2] fragments, allowed the estimation of the Tolman electronic parameter (TEP) for the ligand, which was compared with the TEP value for a related 1,3,5-triphenylbenzene-tris-NHC ligand. The electronic properties of the tris-MIC ligand were studied by cyclic voltammetry measurements. In all cases, the tris-MIC ligand showed a stronger electron-donating character than the corresponding NHC-based ligands. The catalytic activity of the tri-rhodium complex was tested in the addition reaction of arylboronic acids to α,β-unsaturated ketones.

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Section: Resultsmentioning

confidence: 99%

Rhodium, iridium and nickel complexes with a 1,3,5-triphenylbenzene tris-MIC ligand. Study of the electronic properties and catalytic activities

Mejuto¹,

Royo²,

Guisado‐Barrios³

et al. 2015

Beilstein J. Org. Chem.

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“…These results indicate that, while all three complexes are sensitive to the addition of pyrene, 17 is the one that is significantly affected, most probably due to the p-staking of pyrene with the pyrene fragment of the NHC ligand. 22 Although the results shown above indicated that the electrondonating character of the NHC ligand with the extended polyaromatic fragment may be affected by the addition of an external p-stacking additive, we decided to make a more detailed study in order to quantify this effect. For this study, we first calculated the TEP values of a model [Ni(NHC)(CO) 3 ] complex, with NHC = pyrene-imidazolylidene, and then we compared the TEP values obtained for the optimized structures with two p-stacking additives (pyrene and hexafluorobenzene).…”

Section: Ligand-additive Interactions In Metal Complexes With Polyaromentioning

confidence: 99%

Polyaromatic N-heterocyclic carbene ligands and π-stacking. Catalytic consequences

Peris

2016

Chem. Commun.

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In the course of our most recent research, we demonstrated how homogeneous catalysts with polyaromatic functionalities possess properties that clearly differ from those shown by analogues lacking these polyaromatic systems. The differences arise from the ability of the polyaromatic groups to afford non-covalent interactions with aromatic molecules, which can either be substrates in a homogeneous catalysed reaction, or the same catalysts to afford self-assembled systems. This article summarizes all our efforts toward understanding the fundamental effects of π-stacking interactions in homogenous catalysis, particularly in those cases where catalysts bearing polyaromatic functionalities are used. The study reveals several important implications regarding the influence of ligand-ligand interactions, ligand-additive interactions, and ligand-substrate interactions, in the performance of the catalysts used. In particular, the electronic properties of ligands with fused polyconjugated systems, are modified if molecules with π-stacking abilities are added, via a ligand-additive interaction. Also, the kinetics of the reactions in which aromatic substrates and catalysts with polyaromatic ligands are used, are strongly influenced by the self-association of the catalysts and by the non-covalent interaction between the catalyst and the aromatic substrates. The nature and the magnitude of these supramolecular interactions were unveiled by using host-guest chemistry methods applied to organometallic catalysis. Finally, non-covalent interactions afford a very convenient approach for the immobilization of catalysts decorated with polyaromatic systems onto the surfaces of graphene derivatives, hence affording an easy yet extremely effective way to support catalysts and facilitate recycling. The results given have fundamental implications in the design of future catalysts containing rigid polyaromatic systems, and may inspire future researchers in the design of improved homogeneous catalysts, by taking into account that the activities of the metal complexes are strongly modified by supramolecular interactions.

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“…[11] Parallel to this research, we also designed a series of di-and tritopic N-heterocyclic carbene ligands (NHCs) bearing rigid polyaromatic linkers, [12] and found that the catalytic performances of their metal complexes derived were highly influenced by supramolecular effects, which we attributed to the π−π stacking interactions between the polyaromatic spacers of the ligands and the aromatic substrates. [13] For the study of the nature of these supramolecular interactions, a series of complexes with monodentate NHC ligands with rigid polyaromatic backbones were obtained [14] and, by using well-known host-guest chemistry approaches, we were able to determine the nature of the supramolecular interaction and also quantify the extent of the noncovalent binding.…”

Section: Introductionmentioning

confidence: 99%

Platinum‐Based Organometallic Folders for the Recognition of Electron‐Deficient Aromatic Substrates

Nuevo

Gonell

Poyatos

et al. 2017

Chemistry A European J

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A series of platinum complexes with cis-oriented polyaromatic N-heterocyclic carbene ligands were prepared and characterized. The relative disposition of the polyaromatic ligands about the metal make these compounds to behave as a metallofolder, with a cavity defined by the void space between the polyaromatic functionalities. The complexes were used as receptors of organic molecules, where they showed selective affinity for binding electrondeficient aromatic substrates, such as 1,2,4,5-tetracyanobenzene (TCNB), 2,4,7-trinitro-9-fluorenone (TNFLU) and 1,4,5,8-naphtalenetetracarboxylic dianhydride (NTCDA). The binding affinities of two of the metallofolders with these substrates were determined by means of 1 H NMR titrations. Electrospay mass spectrometry (ESI-MS) was also used to assess the affinities. The molecular structure of one of the platinum folders was determined in the presence of TCNB, showing the clear interaction between this guest molecule and the folder formed by the two mutually cis polyaromatic ligands. This work demonstrates how the presence of the mutually cis polyaromatic ligands may constitute a very useful tool for the preparation of metal-based receptors.

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Experimental and Theoretical Approaches to the Influence of the Addition of Pyrene to a Series of Pd and Ni NHC‐Based Complexes: Catalytic Consequences

Cited by 49 publications

References 84 publications

Rhodium, iridium and nickel complexes with a 1,3,5-triphenylbenzene tris-MIC ligand. Study of the electronic properties and catalytic activities

Rhodium, iridium and nickel complexes with a 1,3,5-triphenylbenzene tris-MIC ligand. Study of the electronic properties and catalytic activities

Polyaromatic N-heterocyclic carbene ligands and π-stacking. Catalytic consequences

Platinum‐Based Organometallic Folders for the Recognition of Electron‐Deficient Aromatic Substrates

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