Mechanism of cyclometalation of tris(trimethylphosphine)(neopentyl)iridium(I)

Harper, T. Gregory P.; Desrosiers, Peter J.; Flood, Thomas C.

doi:10.1021/om00159a022

Cited by 28 publications

(19 citation statements)

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“…Examples of 2,2-dimethylmetallacyclobutanes have been reported for a large variety of metals. − Synthesis of metallacycles of this type via cyclometalation of a neopentyl ligand has been found to be relatively general for the late transition metals . Comprehensive mechanistic studies on the cyclometalation of a neopentyl ligand 59,61,63 have led us to propose the mechanism in Scheme .…”

Section: Discussionmentioning

confidence: 99%

C−C and C−H Bond Activation at Ruthenium(II): The Stepwise Degradation of a Neopentyl Ligand to a Trimethylenemethane Ligand

1997

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Ruthenacyclobutane complexes (SiP3)(PMe3)Ru(CH2EMe2CH2) (SiP3 = MeSi(CH2PMe2)3; 1, E = C; 2, E = Si) were synthesized from (SiP3)(PMe3)RuCl2 (3) and 2 equiv of the Grignard reagents, Me3ECH2MgCl. Metallacycle 1 was found to reversibly interconvert with the allyl complex (SiP3)Ru(Me)(η3-CH2CMeCH2) (4) and PMe3 when heated above 75 °C. From the results of kinetic studies and thermolysis of labeled material, the interconversion is proposed to take place by reversible β-methyl elimination/insertion. Conversion of 1 to 4 is an endothermic process (ΔH° = 14.3 ± 1.1 kcal mol-1), but it is entropically favorable (ΔS° = 40.9 ± 2.8 cal K-1 mol-1) due to the loss of the PMe3 ligand. Activation parameters for the β-insertion were determined to be ΔH ⧧ = 26.0 ± 1.2 kcal mol-1 and ΔS ⧧ = −10.5 ± 0.9 cal K-1 mol-1. Allyl complex 4 has been isolated as a mixture of isomers (7:1 endo:exo). The mechanism of interconversion of 4 endo and 4 exo was determined by 1H{31P} NMR spectroscopy (EXSY) to be a process involving a stereochemically rigid, square-pyramidal η1-intermediate. Thermolysis of 4 leads to loss of CH4 and the production of the trimethylenemethane complex (SiP3)Ru(η4-C(CH2)3) (7). The solid state structures of 1 and 7 were determined by X-ray diffraction.

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Section: Discussionmentioning

confidence: 99%

C−C and C−H Bond Activation at Ruthenium(II): The Stepwise Degradation of a Neopentyl Ligand to a Trimethylenemethane Ligand

1997

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“…For the reactions in the absence of acid calculated amounts of the rhodium compound were directly dissolved in the cell with thermostatted toluene. The concentration ranges used were (1)(2)(3)(4)(5) x lo-, mol dm rhodium compound, 0.3-9 mol dm acetic acid, (1.5-10) x 10 mol dm triflic acid and (1-2.5) x 10 mol dm sodium acetate.…”

Section: Methodsmentioning

confidence: 99%

Mechanism of the acid-catalysed cyclometallation reaction of dirhodium(II) compounds with general formula [Rh₂(O₂CMe)(µ-O₂CMe)₂{(C₆H₄)PPh₂}{P(C₆H₄X)}₃}(OH₂)]

González¹,

Lahuerta²,

Martı́nez³

et al. 1994

J. Chem. Soc., Dalton Trans.

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“…Reductive elimination has previously been observed from hexacoordinate d 6 and square planar d 8 metals both with and without prior ancillary ligand dissociation in different cases, suggesting that either pathway might be competent. ,,, While direct observation of this transient intermediate is precluded, some insight into its nature may be gained from the introduction of appropriate nonsolvent neutral donors.…”

Section: Nature Of the Michaelis Complexmentioning

confidence: 98%

Scope and Mechanism of Cooperativity at the Intersection of Organometallic and Supramolecular Catalysis

et al. 2016

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ABSTRACT:The scope and mechanism of the microenvironmentcatalyzed C(sp 3 )−C(sp 3 ) reductive elimination from transition metal complexes [Au(III), Pt(IV)] is explored. Experiments detailing the effect of structural perturbation of neutral and anionic spectator ligands, reactive alkyl ligands, solvent, and catalyst structure are disclosed. Indirect evidence for a coordinatively unsaturated encapsulated cationic intermediate is garnered via observation of several inactive donorarrested inclusion complexes, including a crystallographically characterized encapsulated Au(III) cation. Finally, based on stoichiometric experiments under catalytically relevant conditions, a detailed mechanism is outlined for the dual supramolecular and platinumcatalyzed C−C coupling between methyl iodide and tetramethyltin. Determination of major platinum species present under catalytic conditions and subsequent investigation of their chemistry reveals an unexpected interplay between cis−trans isomerism and the supramolecular catalyst in a Pt(II)/Pt(IV) cycle, as well as several off-cycle reactions.

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Mechanism of cyclometalation of tris(trimethylphosphine)(neopentyl)iridium(I)

Cited by 28 publications

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C−C and C−H Bond Activation at Ruthenium(II): The Stepwise Degradation of a Neopentyl Ligand to a Trimethylenemethane Ligand

C−C and C−H Bond Activation at Ruthenium(II): The Stepwise Degradation of a Neopentyl Ligand to a Trimethylenemethane Ligand

Mechanism of the acid-catalysed cyclometallation reaction of dirhodium(II) compounds with general formula [Rh₂(O₂CMe)(µ-O₂CMe)₂{(C₆H₄)PPh₂}{P(C₆H₄X)}₃}(OH₂)]

Scope and Mechanism of Cooperativity at the Intersection of Organometallic and Supramolecular Catalysis

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Mechanism of cyclometalation of tris(trimethylphosphine)(neopentyl)iridium(I)

Cited by 28 publications

References 0 publications

C−C and C−H Bond Activation at Ruthenium(II): The Stepwise Degradation of a Neopentyl Ligand to a Trimethylenemethane Ligand

C−C and C−H Bond Activation at Ruthenium(II): The Stepwise Degradation of a Neopentyl Ligand to a Trimethylenemethane Ligand

Mechanism of the acid-catalysed cyclometallation reaction of dirhodium(II) compounds with general formula [Rh2(O2CMe)(µ-O2CMe)2{(C6H4)PPh2}{P(C6H4X)}3}(OH2)]

Scope and Mechanism of Cooperativity at the Intersection of Organometallic and Supramolecular Catalysis

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Mechanism of the acid-catalysed cyclometallation reaction of dirhodium(II) compounds with general formula [Rh₂(O₂CMe)(µ-O₂CMe)₂{(C₆H₄)PPh₂}{P(C₆H₄X)}₃}(OH₂)]