Oxidative addition of ether O-methyl bonds at a Pt(0) centre

Jasim, Naseralla A.; Perutz, Robin N.; Procacci, Barbara; Whitwood, Adrian C.

doi:10.1039/c4cc00853g

Cited by 5 publications

(14 citation statements)

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“…3 times shorter in THF than in hexane. 21 According to the previous calculations, that observation can be merely related to the higher dielectric constant of THF ( 7.426) with respect to hexane ( ) which favours the charge separation via S N 2 mechanism.…”

Section: Computational Study Of C O Bond Activation Mechanismmentioning

confidence: 93%

“…These results are in broad agreement with previous experiments, which showed a reaction with a, b, e and f whereas 1-an was not reactive. 21 However, the calculated barriers for b, e and f are not significantly different from one another, while the experimental order of reactivity was b > e > f. Scheme 3 Substrates under study and their corresponding Gibbs activation energies via SN2 mechanism (kcal mol 1 ).…”

Section: O Bond Activation Of Other Substratesmentioning

confidence: 98%

“…For the sake of comparison and further analysis, the S N 2 mechanism has been computed for different methoxy-based substrates as reported experimentally, 21 i.e., a, e, f, and an (Scheme 3a). The van der Waals complexes 1·a, 1·e, 1·f and 1·an are energetically similar to 1·b, in the range of 3 6 kcal mol 1 .…”

Section: O Bond Activation Of Other Substratesmentioning

confidence: 99%

“…with Pt(PCy 3 ) 2 2 in hexane proceeded immediately at room temperature forming a colourless precipitate that was recrystallised from benzene/hexane to yield 2g. Notably, this reaction proceeds much faster than any of those described in ref 21. The molecular structure of 2g was determined by X-ray crystallography as the salt of tetrafluoropyridinolate [Pt(PCy 3 ) 2 ( 3 -allyl)][OC 5 NF 4 ] (Fig.…”

Section: Experimental and Computational Reactivity Toward 2356tetrmentioning

confidence: 99%

“…17c In this paper we follow up the recent report by some of us (Perutz et al) of the activation of C(methyl) O bonds of fluorinated arenes using Pt(PCyp 3 ) 2 . 21 We demonstrated that this substrate reacts with Ar F O Me to form trans-[PtMe(OAr F )(PCyp 3 ) 2 ] (Scheme 1). Notable features of these reactions were selectivity for cleavage of the O CH 3 bond, an increased rate in THF compared to hexane, a negligible kinetic isotope effect for replacement of the OCH 3 group by OCD 3 , a reduction in rate with fewer fluorine substituents, and the absence of reaction with anisole itself.…”

Section: Introductionmentioning

confidence: 98%

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Platinum(0)-mediated C–O bond activation of ethers via an S_N2 mechanism

et al. 2016

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A computational study of the C(methyl)-O bond activation of fluorinated aryl methyl ethers by a platinum(0) complex Pt(PCyp) (Cyp = cyclopentyl) (N. A. Jasim, R. N. Perutz, B. Procacci and A. C. Whitwood, Chem. Commun., 2014, 50, 3914) demonstrates that the reaction proceeds via an S2 mechanism. Nucleophilic attack of Pt(0) generates an ion pair consisting of a T-shaped platinum cation with an agostic interaction with a cyclopentyl group and a fluoroaryloxy anion. This ion-pair is converted to a 4-coordinate Pt(ii) product trans-[PtMe(OAr)(PCyp)]. Structure-reactivity correlations are fully consistent with this mechanism. The Gibbs energy of activation is calculated to be substantially higher for aryl methyl ethers without fluorine substituents and higher still for alkyl methyl ethers. These conclusions are in accord with the experimental results. Further support was obtained in an experimental study of the reaction of Pt(PCy) with 2,3,5,6-tetrafluoro-4-allyloxypyridine yielding the salt of the Pt(η-allyl) cation and the tetrafluoropyridinolate anion [Pt(PCy)(η-allyl)][OCNF]. The calculated activation energy for this reaction is significantly lower than that for fluorinated aryl methyl ethers.

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Section: Computational Study Of C O Bond Activation Mechanismmentioning

confidence: 93%

Section: O Bond Activation Of Other Substratesmentioning

confidence: 98%

Section: O Bond Activation Of Other Substratesmentioning

confidence: 99%

Section: Experimental and Computational Reactivity Toward 2356tetrmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 98%

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Platinum(0)-mediated C–O bond activation of ethers via an S_N2 mechanism

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Methyl Complexes of the Transition Metals

Campos

López‐Serrano

Peloso

et al. 2016

Chemistry A European J

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Organometallic chemistry can be considered as a wide area of knowledge that combines concepts of classic organic chemistry, i.e. based essentially on carbon, with molecular inorganic chemistry, especially with coordination compounds. Transition metal methyl complexes probably represent the simplest and most fundamental way to view how these two major areas of chemistry combine and merge into novel species with intriguing features in terms of reactivity, structure, and bonding. Citing more than 500 bibliographic references, this review aims to offer a concise view of recent advances in the field of transition metal complexes containing M-CH3 fragments. Taking into account the impressive amount of data that are continuously provided by organometallic chemists in this area, this review is mainly focused on results of the last 5 years. After a panoramic overview on M-CH3 compounds of groups 3 to 11 which includes the most recent landmark findings in this area, two further sections are dedicated to methyl-bridged complexes and reactivity.

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Mechanism of Ni-NHC Catalyzed Hydrogenolysis of Aryl Ethers: Roles of the Excess Base

Chung

2015

ACS Catal.

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The transformation of aromatic carbon−oxygen (C Ar −O) bonds in lignin to useful chemical building blocks has great potential in biomass conversion. A Ni-NHC (N-heterocyclic carbene) catalyzed selective hydrogenolysis of aryl ethers has recently been developed by Hartwig and co-worker, but the reaction mechanism, including the role of different additives found to accelerate the reaction and the origin of the selectivity, remains unclear. DFT calculations of several possible pathways for this useful and important transformation suggest a new mechanistic pathway which involves coordination of the excess base ( t BuO − ) to facilitate the rate-determining C−O activation step, dissociation of the ArO − ligand, H 2 activation through a Ni−O t Bu bond to give HO t Bu, and finally reductive elimination to afford the arene product. Another new ion-pair (S N Ar-like) pathway for the base-assisted C−O bond activation could compete with the above base-assisted oxidative addition pathway for some diaryl ethers. The regioselective cleavage of different ethers and the effects of the Lewis acid were also examined and compared. The results demonstrate that bulkiness and strong donating ability of the NHC ligand and the presence of excess base are the keys to a Ni(0)/Ni(II) catalytic cycle.

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Oxidative addition of ether O-methyl bonds at a Pt(0) centre

Abstract: Pt(PCyp3)2 (Cyp = cyclopentyl) undergoes C-O oxidative addition with 2,3,5,6-tetrafluoro-4-methoxypyridine, pentafluoroanisole, 2,3,5,6-tetrafluoroanisole and 2,3,6-trifluoroanisole yielding platinum methyl derivatives. The reactions occur in preference to C-H or C-F activation.

Cited by 5 publications

References 31 publications

Platinum(0)-mediated C–O bond activation of ethers via an S_N2 mechanism

Platinum(0)-mediated C–O bond activation of ethers via an S_N2 mechanism

Methyl Complexes of the Transition Metals

Mechanism of Ni-NHC Catalyzed Hydrogenolysis of Aryl Ethers: Roles of the Excess Base

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Oxidative addition of ether O-methyl bonds at a Pt(0) centre

Abstract: Pt(PCyp3)2 (Cyp = cyclopentyl) undergoes C-O oxidative addition with 2,3,5,6-tetrafluoro-4-methoxypyridine, pentafluoroanisole, 2,3,5,6-tetrafluoroanisole and 2,3,6-trifluoroanisole yielding platinum methyl derivatives. The reactions occur in preference to C-H or C-F activation.

Cited by 5 publications

References 31 publications

Platinum(0)-mediated C–O bond activation of ethers via an SN2 mechanism

Platinum(0)-mediated C–O bond activation of ethers via an SN2 mechanism

Methyl Complexes of the Transition Metals

Mechanism of Ni-NHC Catalyzed Hydrogenolysis of Aryl Ethers: Roles of the Excess Base

Contact Info

Product

Resources

About

Platinum(0)-mediated C–O bond activation of ethers via an S_N2 mechanism

Platinum(0)-mediated C–O bond activation of ethers via an S_N2 mechanism