Activation of carbon-hydrogen bonds in alkanes and other organic molecules by Ir(I), Rh(I) and Ir(III) complexes

Bengali, Ashfaq A.; Arndtsen, Bruce A.; Burger, Peter; Schultz, Richard H.; Weiller, Bruce H.; Kyle, Kevin R.; Moore, C. Bradley; Bergman, Robert G.

doi:10.1351/pac199567020281

Cited by 63 publications

(43 citation statements)

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“…Bergman and co-workers investigated the photolysis of Rh(Cp*)(CO) 2 in low temperature noble gas solutions, doped with alkanes, with TRIR spectroscopy and found evidence for the presence of an organometallic alkane complex as a precursor to C-H activation. However the IR (CO) bands of the alkane complex were not resolvable from those of the initially formed noble gas complex [38,39].…”

Section: The Role Of Organometallic Alkane Complexes In Transition Mementioning

confidence: 93%

Formation and reactivity of organometallic alkane complexes

Cowan

George

2008

Coordination Chemistry Reviews

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Section: The Role Of Organometallic Alkane Complexes In Transition Mementioning

confidence: 93%

Formation and reactivity of organometallic alkane complexes

Cowan

George

2008

Coordination Chemistry Reviews

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“…In these experiments (25), and others similar to them (26)(27)(28)(29), an inverse kinetic isotope effect and H/D exchange between the hydride and alkyl groups before elimination of the alkane indicated the presence of an alkane -complex intermediate. More recently, direct evidence for alkane -complex intermediates was obtained from TRIR flash kinetics studies on the photoinduced COH bond activation by Cp*Rh(CO) 2 in liquid rare gases (30)(31)(32). These experiments showed a reaction intermediate, assigned to be Cp*Rh(CO)(alkane), which became increasingly stable (relative to the reactants) with increasing alkane size, ranging from Ϫ0.9 kcal/mol for ethane to Ϫ2.3 kcal/mol for octane and from Ϫ2.4 kcal/mol for cyclopentane to Ϫ3.5 kcal/mol for cyclooctane (32).…”

Section: Introductionmentioning

confidence: 99%

Theoretical study of the rhenium–alkane interaction in transition metal–alkane σ-complexes

Cobar

Khaliullin

Bergman

et al. 2007

Proc. Natl. Acad. Sci. U.S.A.

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Metal-alkane binding energies have been calculated for [CpRe(CO) 2](alkane) and [(CO)2M(C5H4)C'C(C5H4)M(CO)2](alkane), where M ‫؍‬ Re or Mn. Calculated binding energies were found to increase with the number of metal-alkane interaction sites. In all cases examined, the manganese-alkane binding energies were predicted to be significantly lower than those for the analogous rhenium-alkane complexes. The metal (Mn or Re)-alkane interaction was predicted to be primarily one of charge transfer, both from the alkane to the metal complex (70 -80% of total charge transfer) and from the metal complex to the alkane (20 -30% of the total charge transfer).binding energy ͉ COH activation ͉ DFT calculations ͉ manganese C arbon-hydrogen (COH) bond activation reactions are important from a fundamental point of view, as well as in more practical terms to medicine, academia, and industry, as they are being used for the conversion of common, inexpensive alkanes into reactive (and physiologically active) molecules (1, 2). Many transition metal complexes are now known that can be used to activate COH bonds in alkanes (3). With low-valent metal complexes, the first bond-breaking step involves oxidative addition of an alkane to an unsaturated metal center (Fig. 1). The goal of subsequent steps is to convert the alkyl group R into an alcohol ROH or other potentially useful functionalized organic molecule.Many researchers today are focusing on the development of industrially practical organometallic oxidation catalysts (5-8), but there remain fundamental aspects of the COH activation process that are not fully understood. For instance, it is widely accepted that COH activation reactions proceed via alkane -complex intermediates (3) (Fig. 1, compound 3), and such species have recently been detected and studied in lowtemperature NMR experiments (9-11). Although complexes with intramolecular COH/metal (so-called agostic) interactions have been isolated and crystallographically characterized (3), in systems where strong evidence has been provided for intermolecular metal-alkane coordination in solution (9-11), isolation and solid state structural characterization have not yet been accomplished.† † Intermolecular metal-alkane complexes are therefore one of the most important targets in the study of COH activation; an understanding of the mechanisms of COH activation, which will allow researchers to better control and manipulate the outcome of the reactions, is crucial for the advancement of this area of chemistry.Quantum chemical methods have become useful and practical tools in study of TM complexes (14-17). Particularly, advancements in density functional theory (DFT) (16) and the use of effective core potentials (14, 15) have made qualitatively accurate predictions of the structures and chemistry of TM complexes possible at a reasonable computational cost (17). The goals of the present work are twofold: to make computational predictions of the relative stabilities of a selection of alkane -complexes, which will aid synthetic chemists in th...

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“…The intermediacy of -alkane complexes has been found to play a critical role in these activation reactions (11)(12)(13)(14). Binding of alkanes has been studied experimentally by using time-resolved IR (15)(16)(17) and NMR spectroscopies (18).…”

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confidence: 99%