Structural and dynamic properties of propane coordinated to TpRh(CNR) from a confrontation between theory and experiment

Clot, Eric; Eisenstein, Odile; Jones, William D.

doi:10.1073/pnas.0609454104

Cited by 31 publications

(40 citation statements)

References 49 publications

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“…They computed an activation energy of ∼6.5 kcal/mol for this process. Clot and Eisenstein located a similar transition state for the 1,2‐migration process of the σ‐alkane complexes of [Tp′Rh(CNMe)] (Tp ′ = HB–(3,5‐dimethylpyrazolyl) 3 ) using DFT and estimated a lower activation barrier for this migration compared with the CH activation and alkane dissociation processes in the same system . These results complement, and are consistent with, the experimental reports of Jones …”

Section: Introductionsupporting

confidence: 85%

Contrasting electronic requirements for CH binding and CH activation in d⁶ half‐sandwich complexes of rhenium and tungsten

Thenraj

Samuelson

2015

J Comput Chem

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A computational study of the interaction half-sandwich metal fragments (metal = Re/W, electron count = d(6)), containing linear nitrosyl (NO(+) ), carbon monoxide (CO), trifluorophosphine (PF3 ), N-heterocyclic carbene (NHC) ligands with alkanes are conducted using density functional theory employing the hybrid meta-GGA functional (M06). Electron deficiency on the metal increases with the ligand in the order NHC < CO < PF3 < NO(+). Electron-withdrawing ligands like NO(+) lead to more stable alkane complexes than NHC, a strong electron donor. Energy decomposition analysis shows that stabilization is due to orbital interaction involving charge transfer from the alkane to the metal. Reactivity and dynamics of the alkane fragment are facilitated by electron donors on the metal. These results match most of the experimental results known for CO and PF3 complexes. The study suggests activation of alkane in metal complexes to be facile with strong donor ligands like NHC.

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Section: Introductionsupporting

confidence: 85%

Contrasting electronic requirements for CH binding and CH activation in d⁶ half‐sandwich complexes of rhenium and tungsten

Thenraj

Samuelson

2015

J Comput Chem

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“…However, these studies only examined a limited number of linear alkanes. Although fast time-resolved studies have not been reported for Tp*Rh(CNR)(alkane), activation and reductive elimination for small linear alkane complexes have been studied both experimentally and computationally, where the results parallel those of Tp*Rh(CO)(alkane). − …”

Section: Introductionmentioning

confidence: 99%

Probing the Carbon–Hydrogen Activation of Alkanes Following Photolysis of Tp′Rh(CNR)(carbodiimide): A Computational and Time-Resolved Infrared Spectroscopic Study

et al. 2018

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Carbon-hydrogen bond activation of alkanes by Tp'Rh(CNR) (Tp' = Tp = trispyrazolylborate or Tp* = tris(3,5-dimethylpyrazolyl)borate) were followed by time-resolved infrared spectroscopy (TRIR) in the υ(CNR) and υ(B-H) spectral regions on Tp*Rh(CNCHCMe), and their reaction mechanisms were modeled by density functional theory (DFT) on TpRh(CNMe). The major intermediate species were: κ-η-alkane complex (1); κ-η-alkane complex (2); and κ-alkyl hydride (3). Calculations predict that the barrier between 1 and 2 arises from a triplet-singlet crossing and intermediate 2 proceeds over the rate-determining C-H activation barrier to give the final product 3. The activation lifetimes measured for the Tp*Rh(CNR) and Tp*Rh(CO) fragments with n-heptane and four cycloalkanes (CH, CH, CH, and CH) increase with alkanes size and show a dramatic increase between CH and CH. A similar step-like behavior was observed previously with CpRh(CO) and Cp*Rh(CO) fragments and is attributed to the wider difference in C-H bonds that appear at CH. However, Tp'Rh(CNR) and Tp'Rh(CO) fragments have much longer absolute lifetimes compared to those of CpRh(CO) and Cp*Rh(CO) fragments, because the reduced electron density in dechelated κ-η-alkane Tp' complexes stabilizes the d Rh(I) in a square-planar geometry and weakens the metal's ability for oxidative addition of the C-H bond. Further, the Tp'Rh(CNR) fragment has significantly slower rates of C-H activation in comparison to the Tp'Rh(CO) fragment for the larger cycloalkanes, because the steric bulk of the neopentyl isocyanide ligand hinders the rechelation in κ-Tp'Rh(CNR)(cycloalkane) species and results in the C-H activation without the assistance of the rechelation.

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“…examined the related (4,4′‐dibromotolane)platinum(0) diphoshine complex and observed an initial coordination to the central CC bond followed by CBr oxidative addition 11. Weak interactions between saturated hydrocarbons and metal complexes have been observed as well 4e. 12 However, the use of intramolecular reaction channels to selectively functionalize a compound is rare 13.…”

Section: Introductionmentioning

confidence: 99%

Mechanistic Aspects of Aryl–Halide Oxidative Addition, Coordination Chemistry, and Ring‐Walking by Palladium

Zenkina

Gidron

Shimon

et al. 2015

Chemistry A European J

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This contribution describes the reactivity of a zero-valent palladium phosphine complex with substrates that contain both an aryl halide moiety and an unsaturated carbon-carbon bond. Although η(2) -coordination of the metal center to a C=C or C≡C unit is kinetically favored, aryl halide bond activation is favored thermodynamically. These quantitative transformations proceed under mild reaction conditions in solution or in the solid state. Kinetic measurements indicate that formation of η(2) -coordination complexes are not nonproductive side-equilibria, but observable (and in several cases even isolated) intermediates en route to aryl halide bond cleavage. At the same time, DFT calculations show that the reaction with palladium may proceed through a dissociation-oxidative addition mechanism rather than through a haptotropic intramolecular process (i.e., ring walking). Furthermore, the transition state involves coordination of a third phosphine to the palladium center, which is lost during the oxidative addition as the C-halide bond is being broken. Interestingly, selective activation of aryl halides has been demonstrated by adding reactive aryl halides to the η(2) -coordination complexes. The product distribution can be controlled by the concentration of the reactants and/or the presence of excess phosphine.

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Structural and dynamic properties of propane coordinated to TpRh(CNR) from a confrontation between theory and experiment

Abstract: density functional theory ͉ hydrocarbon activation ͉ rhodium ͉ selectivity

Cited by 31 publications

References 49 publications

Contrasting electronic requirements for CH binding and CH activation in d⁶ half‐sandwich complexes of rhenium and tungsten

Contrasting electronic requirements for CH binding and CH activation in d⁶ half‐sandwich complexes of rhenium and tungsten

Probing the Carbon–Hydrogen Activation of Alkanes Following Photolysis of Tp′Rh(CNR)(carbodiimide): A Computational and Time-Resolved Infrared Spectroscopic Study

Mechanistic Aspects of Aryl–Halide Oxidative Addition, Coordination Chemistry, and Ring‐Walking by Palladium

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Structural and dynamic properties of propane coordinated to TpRh(CNR) from a confrontation between theory and experiment

Abstract: density functional theory ͉ hydrocarbon activation ͉ rhodium ͉ selectivity

Cited by 31 publications

References 49 publications

Contrasting electronic requirements for CH binding and CH activation in d6 half‐sandwich complexes of rhenium and tungsten

Contrasting electronic requirements for CH binding and CH activation in d6 half‐sandwich complexes of rhenium and tungsten

Probing the Carbon–Hydrogen Activation of Alkanes Following Photolysis of Tp′Rh(CNR)(carbodiimide): A Computational and Time-Resolved Infrared Spectroscopic Study

Mechanistic Aspects of Aryl–Halide Oxidative Addition, Coordination Chemistry, and Ring‐Walking by Palladium

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Contrasting electronic requirements for CH binding and CH activation in d⁶ half‐sandwich complexes of rhenium and tungsten

Contrasting electronic requirements for CH binding and CH activation in d⁶ half‐sandwich complexes of rhenium and tungsten