Electrophilic C−H Activation at {Cp*Ir}:  Ancillary-Ligand Control of the Mechanism of C−H Activation

Davies, David; Donald, Steven M. A.; Al-Duaij, Omar K.; Macgregor, Stuart A.; Pölleth, Manuel

doi:10.1021/ja060173+

Cited by 246 publications

(160 citation statements)

References 27 publications

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“…These confirmed the previously reported result [45] that C-H activation proceeds via acetate assistance and not oxidative addition. The subsequent insertion of 4-octyne insertion is thought to be rate limiting and has a transition state at +29.6 kcal/mol.…”

Section: Heterocycle Formation Without Internal Oxidantssupporting

confidence: 92%

Computational Studies on Heteroatom-Assisted C–H Activation and Functionalisation at Group 8 and 9 Metal Centres

Carr

Macgregor

McMullin

2015

C-H Bond Activation and Catalytic Functionalization I

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This chapter surveys computational studies on heteroatom-assisted C-H activation at group 8 and 9 metal centres and will cover the literature since 2009. The chapter first considers work where the mechanism of the C-H activation step is the primary concern and categorizes these into intramolecular (with directing groups) and intermolecular processes. Studies on C-H activation and functionalization will be presented, classified in terms of the nature of the functionalization process (oxidative coupling to form heterocycles, alkenylation and amination).

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Section: Heterocycle Formation Without Internal Oxidantssupporting

confidence: 92%

Computational Studies on Heteroatom-Assisted C–H Activation and Functionalisation at Group 8 and 9 Metal Centres

Carr

Macgregor

McMullin

2015

C-H Bond Activation and Catalytic Functionalization I

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“…(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) have reported the intramolecular C-H bond activation of {Cp*M} (M = Rh, Ir) species. [7] Such base-assisted C-H bond activation is very attractive as an alternative mechanism to oxidative addition. In this context, the Rh III complexes [(Phebox)Rh(OAc) 2 (H 2 O)] [Phebox = 2,6-bis(oxazolinyl)phenyl], [8] which possess an Rh III center and meridional stereochemistry, could be expected to combine the functions of a Lewis acid for coordination of the substrate and a base to act as a proton acceptor during the C-H bond cleavage step (Scheme 2).…”

Section: Introductionmentioning

confidence: 99%

Carbon–Hydrogen Bond Activation of Arenes by a [Bis(oxazolinyl)phenyl]rhodium(III) Acetate Complex

Ito

Nishiyama

2007

Eur J Inorg Chem

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Thermolysis of the rhodium(III) complex [(dm‐Phebox‐dm)Rh(OAc)2(H2O)] [1; dm‐Phebox‐dm = 2,6‐bis(4,4‐dimethyloxazolinyl)phenyl] in various arenes results in the formation of the corresponding aryl complexes [(dm‐Phebox‐dm)Rh(Ar)(κ2‐OAc)] [Ar = C6H5 (2), 3,5‐Me2C6H3 (3), 3,4‐Me2C6H3 (4), C6H4Me (5), C6H4CF3 (6), C6H4OMe (7), C6H4COMe (8), C6H4Cl (9)]. The reaction of 1 with monosubstituted benzenes such as toluene, anisole, acetophenone, trifluorotoluene, and chlorobenzene produces a mixture of meta‐ and para‐activated complexes, the ratio of which depends on the substituents on the benzene ring. The relative rate of the reaction of 1 with monosubstituted benzenes C6H5X was determined to be: X = OMe (1.8) > COMe (1.6) > CF3 (1.2), Cl (1.2) > CH3 (1). The acetato ligand of 1 appears to be essential for C–H bond activation of arenes as no reaction of the RhIII complex [(dm‐Phebox‐dm)RhCl2(H2O)] is observed in chlorobenzene at 120 °C. The first‐order rate constants obtained by thermolysis of 1 in [D8]toluene at 97.1–116.5 °C yielded the following activation parameters: ΔH‡ = 22(2) kcal mol–1, ΔS‡ = –24(5) cal mol–1 K–1. The kinetic isotope effect for the C–H bond activation of toluene by 1 was determined to be kH/kD = 5.4 at 100 °C. These data suggest that the rate‐determining step involves the C–H bond cleavage with a rigid, cyclic transition structure. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)

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“…The mechanism of aromatic CÀH activation at [Cp*Ir] fragments has been studied using the density functional theory by Davies, [13] and although the computed C À H activation barriers are not consistent with the reactivity patterns of experimental studies, a range of carboxylates and triflates have been found to affect cyclometallation.…”

Section: Resultsmentioning

confidence: 99%

Construction of Tetranuclear Macrocycles through CH Activation and Structural Transformation Induced by [2+2] Photocycloaddition Reaction

Han

Lin

et al. 2011

Chemistry A European J

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A series of binuclear complexes [{Cp*Ir(OOCCH(2)COO)}(2)(pyrazine)] (1b), [{Cp*Ir(OOCCH(2)COO)}(2)(bpy)] (2b; bpy=4,4'-bipyridine), [{Cp*Ir(OOCCH(2)COO)}(2)(bpe)] (3b; bpe=trans-1,2-bis(4-pyridyl)ethylene) and tetranuclear metallamacrocycles [{(Cp*Ir)(2)(OOC-C=C-COO)(pyrazine)}(2)] (1c), [{(Cp*Ir)(2)(OOC-C=C-COO)(bpy)}(2)] (2c), [{(Cp*Ir)(2)(OOC-C=C-COO)(bpe)}(2)] (3c), and [{(Cp*Ir)(2)[OOC(H(3)C(6))-N=N-(C(6)H(3))COO](pyrazine)}(2)] (1d), [{(Cp*Ir)(2)[OOC(H(3)C(6))-N=N-(C(6)H(3))COO](bpy)}(2)] (2d), [{(Cp*Ir)(2)[OOC(H(3)C(6))-N=N-(C(6)H(3))COO](bpe)}(2)] (3d) were formed by reactions of 1a-3a {[(Cp*Ir)(2)(pyrazine)Cl(2)] (1a), [(Cp*Ir)(2)(bpy)Cl(2)] (2a), and [(Cp*Ir)(2)(bpe)Cl(2)] (3a)} with malonic acid, fumaric acid, or H(2)ADB (azobenzene-4,4'-chcarboxylic acid), respectively, under mild conditions. The metallamacrocycles were directly self-assembled by activation of C-H bonds from dicarboxylic acids. Interestingly, after exposure to UV/Vis light, 3c was converted to [2+2] cycloaddition complex 4. The molecular structures of 2b, 1c, 1d, and 4 were characterized by single-crystal x-ray crystallography. Nanosized tubular channels, which may play important roles for their stability, were also observed in 1c, 1d, and 4. All complexes were well characterized by (1)H NMR and IR spectroscopy, as well as elemental analysis.

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Electrophilic C−H Activation at {Cp*Ir}: Ancillary-Ligand Control of the Mechanism of C−H Activation

Cited by 246 publications

References 27 publications

Computational Studies on Heteroatom-Assisted C–H Activation and Functionalisation at Group 8 and 9 Metal Centres

Computational Studies on Heteroatom-Assisted C–H Activation and Functionalisation at Group 8 and 9 Metal Centres

Carbon–Hydrogen Bond Activation of Arenes by a [Bis(oxazolinyl)phenyl]rhodium(III) Acetate Complex

Construction of Tetranuclear Macrocycles through CH Activation and Structural Transformation Induced by [2+2] Photocycloaddition Reaction

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