Thermal Activation of Hydrocarbon C−H Bonds by Cp*M(NO) Complexes of Molybdenum and Tungsten

Pamplin, Craig B.; Legzdins, Peter

doi:10.1021/ar0202215

Cited by 123 publications

(97 citation statements)

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“…This is now a well-documented reaction for η 2 -benzyne complexes of several early transition metals. [32][33][34]38 Unsaturated terminal alkyne complexes have also activated CH bonds of hydrocarbons via this mechanism. 39,40 As sketched in Scheme 1, transition states for either 1,2-or 1,3-CH bond cleavage have a distinctive σ-bond metathesis type of geometry, where a proton is formally transferred between two negatively charged carbons.…”

Section: ■ Introductionmentioning

confidence: 99%

β-H Abstraction/1,3-CH Bond Addition as a Mechanism for the Activation of CH Bonds at Early Transition Metal Centers

Romero

Dinoi

et al. 2014

Organometallics

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This article describes the generalization of an overlooked mechanism for CH bond activation at early transition metal centers, namely 1,3-CH bond addition at an η 2 -alkene intermediate. The X-ray-characterized [Cp 2 Zr(c-C 3 H 5 ) 2 ] eliminates cyclopropane by a β-H abstraction reaction to generate the transientA rapidly cleaves the CH bond of furan and thiophene to give the furyl and thienyl complexes [Cp 2 Zr(c-C 3 H 5 )(2-C 4 H 3 X)] (X = O, S), respectively. Benzene is less cleanly activated. Mechanistic investigations including kinetic studies, isotope labeling, and DFT computation of the reaction profile all confirm that rapid stereospecific 1,3-CH bond addition across the Zr(η 2 -alkene) bond of A follows the rate-determining β-H abstraction reaction. DFT computations also suggest that an α-CC agostic rotamer of [Cp 2 Zr(c-C 3 H 5 ) 2 ] assists the β-H abstraction of cyclopropane. The nature of the α-CC agostic interaction is discussed in the light of an NBO analysis.

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Section: ■ Introductionmentioning

confidence: 99%

β-H Abstraction/1,3-CH Bond Addition as a Mechanism for the Activation of CH Bonds at Early Transition Metal Centers

Romero

Dinoi

et al. 2014

Organometallics

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“…Metal-carbon bond formation reactions of transition metals are important in terms of C-H bond activation [1][2][3]. The metal mediated catalytic and stoichiometric organic transformations often involve transient organometallic species in the intermediate steps [4,5].…”

Section: Introductionmentioning

confidence: 99%

Syntheses, characterization, structure and redox properties of new Rh(III) cyclometallates incorporating azoimine ligands

Pratihar

Patra²,

Chattopadhyay

2005

Journal of Organometallic Chemistry

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“…10.1021/acs.organomet.5b00426 Organometallics XXXX, XXX, XXX−XXX H CH 2 CHCHPh) (2), and Cp*W(NO)(H)(η 3 -CH 2 CHCHMe) (3) do not simply effect the single, selective terminal activation of alkane C−H bonds intermolecularly. Rather, they effect two additional successive C−H activations of the hydrocarbon substrates to form new Cp*W(NO)(H)(η 3 -allyl) complexes in which the allyl ligands result from the alkanes being activated.…”

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Thermal Chemistry of Cp*W(NO)(H)(η³-allyl) Complexes

et al. 2015

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The thermal properties of Cp*W(NO)(H)(η 3 -CH 2 CHCMe 2 ) (1), Cp*W(NO)(H)(η 3 -CH 2 CHCHPh) (2), and Cp*W(NO)(H)(η 3 -CH 2 CHCHMe) (3) (Cp* = η 5 -C 5 Me 5 ) have been investigated. Thermolyses of 1−3 in n-pentane lead to the loss of the original allyl ligand and the formation of the same mixture of isomeric products, namely, Cp*W(NO)(H)(η 3 -CH 2 CHCHEt) (4a) and Cp*W(NO)(H)(η 3 -MeCHCHCHMe) (4b) and their coordination isomers. Similarly, 1 reacts with cyclohexane and n-heptane to form Cp*W(NO)(H)(η 3 -C 6 H 9 ) and isomers of Cp*W(NO)(H)(η 3 -C 7 H 13 ), respectively. It is likely that complexes 1−3 first effect the selective, single-terminal C−H activation of the linear alkanes, but the first-formed products are thermally unstable and undergo two additional successive C−H activations to form the final allyl complexes. Consistent with this view is the fact that a bis(alkyl) intermediate complex can be trapped with N-methylmorpholine. Thus, the thermolysis of 1 in Nmethylmorpholine affords a single organometallic complex, Cp*W(NO)(η 2 -CH 2 NC 4 H 8 O)(η 1 -CH 2 CH 2 CHMe 2 ) (7). Complexes 2 and 3 react with N-methylmorpholine in an identical manner. Finally, 1 effects the multiple C−H activations of 1-chloropropane and 1-chlorobutane and forms the corresponding Cp*W(NO)(Cl)(η 3 -allyl) complexes. All new complexes have been characterized by conventional spectroscopic and analytical methods, and the solid-state molecular structures of most of them have been established by single-crystal X-ray crystallographic analyses.

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Thermal Activation of Hydrocarbon C−H Bonds by Cp*M(NO) Complexes of Molybdenum and Tungsten

Cited by 123 publications

References 33 publications

β-H Abstraction/1,3-CH Bond Addition as a Mechanism for the Activation of CH Bonds at Early Transition Metal Centers

β-H Abstraction/1,3-CH Bond Addition as a Mechanism for the Activation of CH Bonds at Early Transition Metal Centers

Syntheses, characterization, structure and redox properties of new Rh(III) cyclometallates incorporating azoimine ligands

Thermal Chemistry of Cp*W(NO)(H)(η³-allyl) Complexes

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Thermal Activation of Hydrocarbon C−H Bonds by Cp*M(NO) Complexes of Molybdenum and Tungsten

Cited by 123 publications

References 33 publications

β-H Abstraction/1,3-CH Bond Addition as a Mechanism for the Activation of CH Bonds at Early Transition Metal Centers

β-H Abstraction/1,3-CH Bond Addition as a Mechanism for the Activation of CH Bonds at Early Transition Metal Centers

Syntheses, characterization, structure and redox properties of new Rh(III) cyclometallates incorporating azoimine ligands

Thermal Chemistry of Cp*W(NO)(H)(η3-allyl) Complexes

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Thermal Chemistry of Cp*W(NO)(H)(η³-allyl) Complexes