One‐Electron versus Two‐Electron Mechanisms in the Oxidative Addition Reactions of Chloroalkanes to Amido‐Bridged Rhodium Complexes

Tejel, Cristina; Ciriano, Miguel A.; López, José A.; Jiménez, Sonia; Bordonaba, Marta; Oro, Luis A.

doi:10.1002/chem.200600971

Cited by 25 publications

(7 citation statements)

References 50 publications

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“…3-Cl can also be generated by photolysis of 2 in methylene chloride at low temperature (eq 4, Figure b). Oxidative addition of the C–Cl bond of dichloromethane − and chloroform to rhodium(I) has been observed previously. …”

Section: Resultssupporting

confidence: 58%

Oxidative Addition of Chlorohydrocarbons to a Rhodium Tris(pyrazolyl)borate Complex

2015

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The reactive fragment [Tp′Rh(PMe 3 )], generated from the thermal precursor Tp′Rh(PMe 3 )(Me)H, is found to cleave the C−Cl bonds of chlorohydrocarbons under mild conditions. Reaction with chloromethane gives clean formation of an initial C−H activation product, which rearranges to form the C−Cl activation product at 30 °C. Reaction with dichloromethane or benzyl chloride gives a mixture of C−Cl activation products as well as products from chlorination. Reaction with chlorocyclohexane gives a mixture of intermediates from C−H activation, which react further upon heating to give a C−Cl cleavage product as well as the β-chloride elimination product Tp′Rh(PMe 3 )(Cl)H plus cyclohexene. Complete conversion from a C−H activation product to a C−Cl activation product was observed in the reaction with 1,2-dichloroethylene, where β-elimination is circumvented. Activation of 1-chlorobutane, 1,2dichloroethane, or 1,4-dichlorobutane gives a mixture of C−Cl activation products as well as Tp′Rh(PMe 3 )(Cl)H plus olefin. Similar to the case for activation of methylene chloride, C−Cl activation and hydride/chloride exchange was observed in the reaction with benzyl chloride, where C−H activation was not seen. The reaction with chlorobenzene gives isomeric species resulting from C−H activation, which react further to give the corresponding chloride derivatives upon heating. Reaction with pentachlorobenzene gives a cyclometalated product from C−H bond cleavage in the phosphine ligand. These reactions are compared and contrasted with related photoreactions with the [Tp′Rh(CNneopentyl)] analogue, where C−H activation is solely observed in most cases. Mechanistic studies suggest the spectator ligand dependent reactivity relies greatly on the dissociation energy of the Tp′Rh−L bond.

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Section: Resultssupporting

confidence: 58%

Oxidative Addition of Chlorohydrocarbons to a Rhodium Tris(pyrazolyl)borate Complex

2015

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“…Scheme illustrates the square scheme for the present case, showing calculated structures and energy differences. The calculations confirm that this indirect oxidative addition at the metal involving one-electron exchange , on the ligand is made possible through the participation of a noninnocently behaving ligand while maintaining a formally invariant metal oxidation state.…”

Section: Resultsmentioning

confidence: 60%

Reversible Intramolecular Single-Electron Oxidative Addition Involving a Hemilabile Noninnocent Ligand

et al. 2011

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“…[8] Further, studies of the oxidative addition reactions of halocarbons allowed the synthesis of Ir I /Ir III derivatives [9] and the detection of S N 2 profiles in the activation of chloro compounds. [10] Herein we report on the synthesis of new dinuclear amido complexes of rhodium and iridium derived from aziridines as well as on their electrochemical behavior. We were searching for dinuclear complexes with aminyl radical character.…”

Section: Ma C H T U N G T R E N N U N G (Ncme)a C H T U N G T R E N Nmentioning

confidence: 99%

Intervalent Bis(μ‐aziridinato)M^IIM^I Complexes (M=Rh, Ir): Delocalized Metallo‐Radicals or Delocalized Aminyl Radicals?

Tejel

Ciriano

Passarelli

et al. 2008

Chemistry A European J

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Reactions of the methoxo complexes [{M(mu-OMe)(cod)}(2)] (cod=1,5-cyclooctadiene, M=Rh, Ir) with 2,2-dimethylaziridine (Haz) give the mixed-bridged complexes [{M(2)(mu-az)(mu-OMe)(cod)(2)}] [(M=Rh, 1; M=Ir, 2). These compounds are isolated intermediates in the stereospecific synthesis of the amido-bridged complexes [{M(mu-az)(cod)}(2)] (M=Rh, 3; M=Ir, 4). The electrochemical behavior of 3 and 4 in CH(2)Cl(2) and CH(3)CN is greatly influenced by the solvent. On a preparative scale, the chemical oxidation of 3 and 4 with [FeCp(2)](+) gives the paramagnetic cationic species [{M(mu-az)(cod)}(2)](+) (M=Rh, [3](+); M=Ir, [4](+)). The Rh complex [3](+) is stable in dichloromethane, whereas the Ir complex [4](+) transforms slowly, but quantitatively, into a 1:1 mixture of the allyl compound [(eta(3),eta(2)-C(8)H(11))Ir(mu-az)(2)Ir(cod)] ([5](+)) and the hydride compound [(cod)(H)Ir(mu-az)(2)Ir(cod)] ([6](+)). Addition of small amounts of acetonitrile to dichloromethane solutions of [3](+) and [4](+) triggers a fast disproportionation reaction in both cases to produce equimolecular amounts of the starting materials 3 and 4 and metal--metal bonded M(II)--M(II) species. These new compounds are isolated by oxidation of 3 and 4 with [FeCp(2)](+) in acetonitrile as the mixed-ligand complexes [(MeCN)(3)M(mu-az)(2)M(NCMe)(cod)](PF(6))(2) (M=Rh, [8](2+); M=Ir, [9](2+)). The electronic structures of [3](+) and [4](+) have been elucidated through EPR measurements and DFT calculations showing that their unpaired electron is primarily delocalized over the two metal centers, with minor spin densities at the two bridging amido nitrogen groups. The HOMO of 3 and 4 and the SOMO of [3](+) and [4](+) are essentially M--M d-d sigma*-antibonding orbitals, explaining the formation of a net bonding interaction between the metals upon oxidation of 3 and 4. Mechanisms for the observed allylic H-atom abstraction reactions from the paramagnetic (radical) complexes are proposed.

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One‐Electron versus Two‐Electron Mechanisms in the Oxidative Addition Reactions of Chloroalkanes to Amido‐Bridged Rhodium Complexes

Cited by 25 publications

References 50 publications

Oxidative Addition of Chlorohydrocarbons to a Rhodium Tris(pyrazolyl)borate Complex

Oxidative Addition of Chlorohydrocarbons to a Rhodium Tris(pyrazolyl)borate Complex

Reversible Intramolecular Single-Electron Oxidative Addition Involving a Hemilabile Noninnocent Ligand

Intervalent Bis(μ‐aziridinato)M^IIM^I Complexes (M=Rh, Ir): Delocalized Metallo‐Radicals or Delocalized Aminyl Radicals?

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One‐Electron versus Two‐Electron Mechanisms in the Oxidative Addition Reactions of Chloroalkanes to Amido‐Bridged Rhodium Complexes

Cited by 25 publications

References 50 publications

Oxidative Addition of Chlorohydrocarbons to a Rhodium Tris(pyrazolyl)borate Complex

Oxidative Addition of Chlorohydrocarbons to a Rhodium Tris(pyrazolyl)borate Complex

Reversible Intramolecular Single-Electron Oxidative Addition Involving a Hemilabile Noninnocent Ligand

Intervalent Bis(μ‐aziridinato)MIIMI Complexes (M=Rh, Ir): Delocalized Metallo‐Radicals or Delocalized Aminyl Radicals?

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Intervalent Bis(μ‐aziridinato)M^IIM^I Complexes (M=Rh, Ir): Delocalized Metallo‐Radicals or Delocalized Aminyl Radicals?