A computational study on the identity of the active catalyst structure for Ru(<scp>ii</scp>) carboxylate assisted C–H activation in acetonitrile

McMullin, Claire L.; Rajabi, Nasir A.; Hammerton, James S

doi:10.1039/c9ob01092k

Cited by 4 publications

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References 30 publications

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“…Oxidative addition of a C–H bond from one of the methyl of the t -butyl group of the imidazole-2-ylidene moiety and release of the 1,5-cyclooctadiene ligand should lead to the formation of cyclometalated M(III) hydrido complexes C with the polydentate ligand κ 4 C , C′ , N , N′ coordinated. As the oxidative addition of the C–H bond in rhodium complexes is likely to be more energy-demanding than in iridium complexes, it cannot be ruled out that the C–H activation could also occur with the intervention of the acetate anion present in the reaction medium via a concerted metalation-deprotonation (CMD) mechanism . Then, due to the likely acidic character of the hydride ligand, the following deprotonation by the acetate base should result in the formation of the square-planar M(I) intermediates [M{κ 4 C , C ′, N , N ′-(CH 2 CMe 2 ImCH 2 PyCH 2 NR 2 )}] ( D ) .…”

Section: Resultsmentioning

confidence: 99%

Rhodium and Iridium Complexes of Lutidine-Based NHC/Amino Pincer Ligands: From Monodentate to Tetradentate Coordination Enabled by C–H Activation

González-Lainez,

Jiménez,

Passarelli

et al. 2023

Organometallics

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A series of rhodium and iridium complexes derived from lutidine-based ligands (lutidine, 2,6-dimethylpyridine) with NHC and amino side-donor functions have been prepared and characterized. Deprotonation of the functionalized imidazolium salts, [ t BuHImCH 2 PyCH 2 NR 2 ]Br, by the bridging methoxo ligands of the dinuclear complexes [M(μ-OMe)(cod)] 2 affords [MBr-(cod)(κC-t BuImCH 2 PyCH 2 NR 2 )] (M = Rh and Ir) complexes from which a series of Rh(I) and Ir(I) complexes including [are readily accessible by halide abstraction and/or carbonylation reactions. In contrast, direct metalation of imidazolium salts with the dinuclear compounds [M(μ-Cl)(cod)] 2 (M = Rh and Ir) in the presence of potassium acetate and potassium iodide, a well-established synthetic route to M(III) species, provides access to unusual di-iodido M(III) cyclometalated compounds [MI 2 {κ 4 C,C′,N,N′-(CH 2 CMe 2 ImCH 2 PyCH 2 NR 2 )}] in low yield. Experimental studies combined with DFT calculations suggest that cyclometalated M(III) hydrido [MH(CH 3 CN){κ 4 C,C′,N,N′-(CH 2 CMe 2 ImCH 2 PyCH 2 NR 2 )}] + compounds and square-planar cyclometalated M(I) [M{κ 4 C,C′,N,N′-(CH 2 CMe 2 ImCH 2 PyCH 2 NR 2 )}] species resulting from their deprotonation by acetate could be intermediates involved in the formation of these compounds. Based on the observed formation of elemental rhodium, disproportionation of square-planar cyclometalated M(I) complexes to afford M(0) and the cationic M(II) species [M{κ 4 C,C′,N,N′-(CH 2 CMe 2 ImCH 2 PyCH 2 NR 2 )}] + is proposed. Reaction of the latter with iodide (I − ) would regenerate the M(I) intermediate to give an iodo radical (I•) that in turn could dimerize to form diiodine I 2 . In this regard, DFT calculations have shown that the oxidative addition of diiodine to the cyclometalated M(I) intermediates leading to the di-iodido M(III) cyclometalated compounds is a highly exergonic process.

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Section: Resultsmentioning

confidence: 99%

Rhodium and Iridium Complexes of Lutidine-Based NHC/Amino Pincer Ligands: From Monodentate to Tetradentate Coordination Enabled by C–H Activation

González-Lainez,

Jiménez,

Passarelli

et al. 2023

Organometallics

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C−H Bond Activation in Ru‐Catalyzed Reactions of Arenes with Olefins: Theoretical Insights into Hydroarylation and Oxidative Coupling Mechanisms

Efremenko

Martin

2023

Israel Journal of Chemistry

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A detailed mechanistic density functional theory (DFT) and coupled cluster study of Csp²−H activation in benzene and methyl acrylate by the catalyst RuClm(CO)n (m=2,3; n=0–4) is presented. We trace the entire reaction pathways from the precursor to the active form of the catalysts followed by catalytic hydroarylation and oxidative coupling reactions. Our results reveal that both computational methods provide very similar qualitative pictures, but only the coupled cluster DLPNO‐CCSD(T1) results are quantitatively consistent with experiment. At the latter level of theory, the Ru(II) and Ru(III) catalyst precursors transform into the same active form of the catalyst, which explains the experimental results. Oxidative addition is extremely endergonic, especially in the presence of CO. Oxidative hydrogen migration (OHM) occurs in complexes with a low Ru coordination number and leads to olefine hydroarylation. Strongly bound carbonyl ligands suppress this interaction. Concerted metalation‐deprotonation (CMD) of the aromatic C−H bond and σ‐bond metathesis mechanisms of catalyst regeneration do not involve Ru−H bonding and form the energetically favorable catalytic cycle of the oxidative coupling reaction. The key interaction in CMD mechanisms consists of proton abstraction by an inner‐sphere Cl‐anion. Carbonyl ligands facilitate CMD by weakening the Ru−Cl bond. An excess of CO slows the interaction by leading to replacement of the reactants in the Ru coordination sphere.

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DLPNO-CCSD(T) and DFT study of the acetate-assisted C–H activation of benzaldimine at [RuCl₂(p-cymene)]₂: the relevance of ligand exchange processes at ruthenium(ii) complexes in polar protic media

Ojea,

Ruiz

2024

Dalton Trans.

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A computational study on the identity of the active catalyst structure for Ru(ii) carboxylate assisted C–H activation in acetonitrile

Abstract: Density Functional Theory (DFT) calculations using a consistent methodology accounting for solvation, dispersion and thermal effects have been used to study C–H activation of the simple directing group substrate 2-phenylpyridine (a-H).

Cited by 4 publications

References 30 publications

Rhodium and Iridium Complexes of Lutidine-Based NHC/Amino Pincer Ligands: From Monodentate to Tetradentate Coordination Enabled by C–H Activation

Rhodium and Iridium Complexes of Lutidine-Based NHC/Amino Pincer Ligands: From Monodentate to Tetradentate Coordination Enabled by C–H Activation

C−H Bond Activation in Ru‐Catalyzed Reactions of Arenes with Olefins: Theoretical Insights into Hydroarylation and Oxidative Coupling Mechanisms

DLPNO-CCSD(T) and DFT study of the acetate-assisted C–H activation of benzaldimine at [RuCl₂(p-cymene)]₂: the relevance of ligand exchange processes at ruthenium(ii) complexes in polar protic media

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A computational study on the identity of the active catalyst structure for Ru(ii) carboxylate assisted C–H activation in acetonitrile

Abstract: Density Functional Theory (DFT) calculations using a consistent methodology accounting for solvation, dispersion and thermal effects have been used to study C–H activation of the simple directing group substrate 2-phenylpyridine (a-H).

Cited by 4 publications

References 30 publications

Rhodium and Iridium Complexes of Lutidine-Based NHC/Amino Pincer Ligands: From Monodentate to Tetradentate Coordination Enabled by C–H Activation

Rhodium and Iridium Complexes of Lutidine-Based NHC/Amino Pincer Ligands: From Monodentate to Tetradentate Coordination Enabled by C–H Activation

C−H Bond Activation in Ru‐Catalyzed Reactions of Arenes with Olefins: Theoretical Insights into Hydroarylation and Oxidative Coupling Mechanisms

DLPNO-CCSD(T) and DFT study of the acetate-assisted C–H activation of benzaldimine at [RuCl2(p-cymene)]2: the relevance of ligand exchange processes at ruthenium(ii) complexes in polar protic media

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DLPNO-CCSD(T) and DFT study of the acetate-assisted C–H activation of benzaldimine at [RuCl₂(p-cymene)]₂: the relevance of ligand exchange processes at ruthenium(ii) complexes in polar protic media