Cyclopropane adducts of platinum(IV): the stabilisation of an ylide

Bailey, Neil A.; Gillard, R. D.; Keeton, Morris T.; Mason, Roger A.; Russell, David R.

doi:10.1039/c19660000396

Cited by 11 publications

(7 citation statements)

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“…To date, most examples of C−C bond cleavage by transition metals have been stoichiometric, often relying on ring strain, prearomaticity, or intramolecular addition in which the C−C bond is “forced” into close proximity to the metal …”

Section: Introductionmentioning

confidence: 99%

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Mechanistic Investigation of Catalytic Carbon−Carbon Bond Activation and Formation by Platinum and Palladium Phosphine Complexes

1998

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The complexes Pt(PEt3)3 and Pd(PEt3)3 cleave the C−C bond of biphenylene to give (PEt3)2Pt(2,2‘-biphenyl), 1, and (PEt3)2Pd(2,2‘-biphenyl), respectively. Heating (PEt3)2Pt(2,2‘-biphenyl) in the presence of biphenylene leads to C−C cleavage of a second biphenylene to give (PEt3)2Pt(2,2‘-tetraphenyl), 2, via a Pt(IV) intermediate. 2 reductively eliminates tetraphenylene at 115 °C. At 120 °C the reaction is catalytic; Pt(PEt3)3 or 1 converts biphenylene to tetraphenylene. The intermediates in the catalytic cycle have been identified, and 1 and 2 have been characterized by X-ray analysis. Under catalytic conditions 1 and 2 approach steady-state concentrations. Kinetic analysis reveals that the steady-state concentration ratio, resting state species, and overall rate of catalysis, k obs, depend on the ratio of biphenylene to PEt3. This observation is consistent with loss of PEt3 from 1, resulting in the 14-electron species (PEt3)Pt(2,2‘-biphenyl), I. At 130 °C, I coordinates to PEt3 approximately 130 times faster than it activates the C−C bond of biphenylene. The complex (depe)Pt(2,2‘-biphenyl), 7 (depe = bis(diethylphosphino)ethane), does not cleave the C−C bond of biphenylene. Compound 2 is also capable of activating the C−H bonds of benzene and biphenylene to give trans-(PEt3)2Pt(α-biphenyl)(phenyl), 5, and trans-(PEt3)2Pt(α-biphenyl)(α-biphenylenyl), 6, respectively. Compounds 5 and 6 have been characterized by X-ray analysis. Substitution of Pd for Pt results in more rapid catalysis; (PEt3)2Pd(2,2‘-biphenyl) is a very efficient catalyst (20 turnovers/h at 120 °C).

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Section: Introductionmentioning

confidence: 99%

“…β-Alkyl migration has been observed with electrophilic early transition metal complexes , Vollhardt et al achieved a catalytic reaction in which tetraphenylene and derivatives of tetraphenylene were catalytically formed from biphenylene derivatives using Ni(COD)(PMe 3 ) 2 3g the mechanism shown in eq 1 was proposed.…”

Section: Introductionmentioning

confidence: 99%

Mechanistic Investigation of Catalytic Carbon−Carbon Bond Activation and Formation by Platinum and Palladium Phosphine Complexes

1998

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“…The insertion of transition-metal atoms into a carbon−carbon bond through oxidative addition is known for many type of hydrocarbons, especially strained-ring compounds and compounds which become aromatic on C−C cleavage . The biphenylene ligand itself has been known for many years .…”

Section: Introductionmentioning

confidence: 99%

C−H versus C−C Activation of Biphenylene in Its Reactions with Iron Group Carbonyl Clusters

Yeh¹,

Hsu²,

Peng³

et al. 1998

Organometallics

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Co-thermolysis of biphenylene ((C 6 H 4 ) 2 ) with Fe 3 (CO) 12 or Fe 2 (CO) 9 leads to activation of a biphenylene C-C bond to generate Fe 2 (CO) 5 (µ-CO)(µ-η 2 ,η 4 -(C 6 H 4 ) 2 ) (1). Similar reaction with Ru 3 (CO) 12 affords Ru 2 (CO) 5 (µ-CO)(µ-η 2 ,η 4 -(C 6 H 4 ) 2 ) (2) and Ru 6 (CO) 17 (µ 6 -C) (3), and the reaction with Os 3 (CO) 12 affords Os 2 (CO) 6 (µ-η 2 ,η 4 -(C 6 H 4)2 ) (4) and Os 4 (CO) 12 (µ 4 -η 2 -(C 6 H 3 )Ph) (5). In contrast, treating biphenylene with Os 3 (CO) 10 (NCMe) 2 leads to C-H bond activation to give (µ-H) 2 Os 3 (CO) 9 (µ 3 -η 2 -C 6 H 2 (C 6 H 4 )) ( 6). The new compounds have been characterized by elemental analyses and mass, IR, and NMR spectroscopy. The structures of 2, 4, and 5 were determined by an X-ray diffraction study. Compound 2 and 4 can be viewed to contain a metallacyclopentadienyl unit which binds the other metal atom in an η 5 -fashion. Compound 5 is the first butterfly cluster of the type Os 4 (CO) 12 (aryne).

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“…We, therefore, resorted to transition‐metal chemistry to effect ring opening in a C−C bond activation process . Tipper reported in 1955 that cyclopropane reacts with platinum(II) chloride to give a complex subsequently shown to contain a platinacyclobutane . Several groups have shown that, when the cyclopropane is substituted with an alcohol or ether group, the platinacyclobutane is unstable and undergoes ring opening .…”

Section: Resultsmentioning

confidence: 99%

“…Given that an iminium ion is proposed as an intermediate, we attempted to trap this with an added nucleophile as achieved by Madsen in the tetrahydropyran series . No such adduct could be isolated upon addition of methanol, benzyl alcohol, acetic acid or allyl trimethylsilane.…”

Section: Resultsmentioning

confidence: 99%

Platinum‐Catalysed Ring‐Opening Isomerisation of Piperidine Cyclopropanes

2018

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Ar ange of cyclopropyl-fused N-tosyl piperidines have been synthesised ands hown to undergo ring-opening isomerisation on treatment with platinum(II) catalysts. The products can have either an endo-cyclic or exo-cyclic double bond. The selectivity is influenced by reaction temperature, solventa nd, most significantly,t he catalyst. Am echanism in-volvingC ÀCb ond activation and b-hydride eliminationi s proposed. When b-hydride elimination is blocked, as tereospecific platinum-driven Wagner-Meerwein shift is observed.

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Cyclopropane adducts of platinum(IV): the stabilisation of an ylide

Cited by 11 publications

References 0 publications

Mechanistic Investigation of Catalytic Carbon−Carbon Bond Activation and Formation by Platinum and Palladium Phosphine Complexes

Mechanistic Investigation of Catalytic Carbon−Carbon Bond Activation and Formation by Platinum and Palladium Phosphine Complexes

C−H versus C−C Activation of Biphenylene in Its Reactions with Iron Group Carbonyl Clusters

Platinum‐Catalysed Ring‐Opening Isomerisation of Piperidine Cyclopropanes

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