A density functional study on the activation of hydrogen-hydrogen and hydrogen-carbon bonds by Cp2Sc-H and Cp2Sc-CH3

Ziegler, Thomas; Folga, E.; Bérces, Attila

doi:10.1021/ja00055a037

Cited by 172 publications

(119 citation statements)

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“…The C(2)-Fe-C(1) angle 83.28, which is small, implies a fourcenter structure close to that found in previous theoretical work on scandium. [21,26] The C(2) ¥¥¥ H distance in TpRuMeTS is significantly longer than that in TpOsMeTS. The former is 1.707 ä and the latter is 1.394 ä.…”

Section: Computational Detailsmentioning

confidence: 95%

“…[21,22] For the Ru system, whose endothermicity is lower than that for Fe system, a relatively long H(1) ¥¥¥ H(2) distance (1.617 ä) and a large C-M-H(1) angle (106.38) are found in the transition state TpRuHTS. The C ¥¥¥ H(2) distance in TpRuHTS is also quite long (1.589 ä).…”

Section: Computational Detailsmentioning

confidence: 98%

“…[21,22,26] Although Fe is a late transition metal, the metal does not favor a high oxidation state. For comparison, we have also studied the metathesis processes with the analogous complexes [Cp(PH 3 )FeR] (R H or CH 3 ).…”

Section: Computational Detailsmentioning

confidence: 99%

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Theoretical Studies on the Metathesis Processes, [Tp(PH₃)MR(η²‐HCH₃)] → [Tp(PH₃)M(CH₃)(η²‐HR)] (M=Fe, Ru, and Os; R=H and CH₃)

Lam

Jia

Lin

et al. 2003

Chemistry A European J

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Theoretical calculations on the metathesis process, [Tp(PH3)MR(eta 2-H[bond]CH3)] --> [Tp(PH3)M(CH3)(eta 2-H[bond]R)] (M=Fe, Ru, and Os; R=H and CH3), have been systematically carried out to study their detailed reaction mechanisms. Other than the one-step mechanism via a four-center transition state and the two-step mechanism through an oxidative addition/reductive elimination pathway, a new one-step mechanism, with a transition state formed under oxidative addition, has been found. Based on the intrinsic reaction coordinate calculations, we found that the trajectories of the transferring hydrogen atom in the metathesis processes studied are similar to each other regardless of the nature of reaction mechanisms.

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Section: Computational Detailsmentioning

confidence: 95%

Section: Computational Detailsmentioning

confidence: 98%

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Theoretical Studies on the Metathesis Processes, [Tp(PH₃)MR(η²‐HCH₃)] → [Tp(PH₃)M(CH₃)(η²‐HR)] (M=Fe, Ru, and Os; R=H and CH₃)

Lam

Jia

Lin

et al. 2003

Chemistry A European J

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“…Consequently, non-solvated rare-earth-metal-methyl complexes were classified as the most reactive organolanthanide compounds. [9] The trianionic hexamethylate complexes [LnA C H T U N G T R E N N U N G {(m-Me) 2 Li(L)} 3 ] (L= N,N,N',N'-tetramethyl-1,2-ethane or 1,2-dimethoxyethane), first reported by Schumann and co-workers, [10] 4 ] by way of the in situ generated, THF-solvated analogue [LnA C H T U N G T R E N N U N G {(mMe) 2 LiA C H T U N G T R E N N U N G (thf) n } 3 ]. [4,11] The tris(tetramethylaluminates) of the rare-earth metals, first reported by Evans et al, [12] have also been used for this purpose.…”

Section: Crown-4)a C H T U N G T R E N N U N G (Thf) 2 ] + a C H T U mentioning

confidence: 99%

CH Activation versus Yttrium–Methyl Cation Formation from [Y(AlMe₄)₃] Induced by Cyclic Polynitrogen Bases: Solvent and Substituent‐Size Effects

Bojer

Venugopal

Mix

et al. 2011

Chemistry A European J

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The reaction of 1,3,5-triisopropyl-1,3,5-triazacyclohexane (TiPTAC) with [Y(AlMe(4))(3)] resulted in the formation of [(TiPTAC)Y(Me(3)AlCH(2)AlMe(3))(μ-MeAlMe(3))] by C-H activation and methane extrusion. In contrast, the presence of bulkier cyclohexyl groups on the nitrogen atoms in 1,3,5-tricyclohexyl-1,3,5-triazacyclohexane (TCyTAC) led to the formation of the cationic dimethyl complex [(TCyTAC)(2)YMe(2)][AlMe(4)]. The investigations reveal a dependency of the reaction mechanism on the steric bulk of the N-alkyl entity and the solvent employed. In toluene C-H activation was observed in reactions of [Y(AlMe(4))(3)] with 1,3,5-trimethyl-1,3,5-triazacyclohexane (TMTAC) and TiPTAC. In THF molecular dimethyl cations, such as [(TCyTAC)(2)YMe(2)][AlMe(4)], [(TMTAC)(2)YMe(2)][AlMe(4)] and [(TiPTAC)(2)YMe(2)][AlMe(4)], could be synthesised by addition of the triazacyclohexane at a later stage. The THF-solvated complex [YMe(2)(thf)(5)][AlMe(4)] could be isolated and represents an intermediate in these reactions. It shows that cationic methyl complexes of the rare-earth metals can be formed by donor-induced cleavage of the rare-earth-metal tetramethylaluminates. The compounds were characterised by single-crystal X-ray diffraction or multinuclear and variable-temperature NMR spectroscopy, as well as elemental analyses. Variable-temperature NMR spectroscopy illustrates the methyl group exchange processes between the cations and anions in solution.

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“…[8][9][10][15][16][17] A more specific example illustrates a prototype reaction treated by experiment [18] and theory. [19] Reaction [22] Dehydrocoupling of silanes to form polysilanes with d 0 metal complexes also proceeds through s-bond metathesis. [23] 3.…”

Section: Introductionmentioning

confidence: 99%

The σ‐CAM Mechanism: σ Complexes as the Basis of σ‐Bond Metathesis at Late‐Transition‐Metal Centers

2007

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Complexes in which a sigma-H--E bond (E=H, B, Si, C) acts as a two-electron donor to the metal center are called sigma complexes. Clues that it is possible to interconvert sigma ligands without a change in oxidation state derive from C--H activation reactions effecting isotope exchange and from dynamic rearrangements of sigma complexes (see Frontispiece). Through these pathways, metathesis of M--E bonds can occur at late transition metals. We call this process sigma-complex-assisted metathesis, or sigma-CAM, which is distinct from the familiar sigma-bond metathesis (typical for d(0) metals and requiring no intermediate) and from oxidative-reductive elimination mechanisms (inherently requiring intermediates with changed oxidation states and sometimes involving sigma complexes). There are examples of sigma-CAM mechanisms in catalysis, especially for alkane borylation and isotope exchange of alkanes. It may also occur in silylation and alkene hydrogenation.

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A density functional study on the activation of hydrogen-hydrogen and hydrogen-carbon bonds by Cp2Sc-H and Cp2Sc-CH3

Cited by 172 publications

References 1 publication

Theoretical Studies on the Metathesis Processes, [Tp(PH₃)MR(η²‐HCH₃)] → [Tp(PH₃)M(CH₃)(η²‐HR)] (M=Fe, Ru, and Os; R=H and CH₃)

Theoretical Studies on the Metathesis Processes, [Tp(PH₃)MR(η²‐HCH₃)] → [Tp(PH₃)M(CH₃)(η²‐HR)] (M=Fe, Ru, and Os; R=H and CH₃)

CH Activation versus Yttrium–Methyl Cation Formation from [Y(AlMe₄)₃] Induced by Cyclic Polynitrogen Bases: Solvent and Substituent‐Size Effects

The σ‐CAM Mechanism: σ Complexes as the Basis of σ‐Bond Metathesis at Late‐Transition‐Metal Centers

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A density functional study on the activation of hydrogen-hydrogen and hydrogen-carbon bonds by Cp2Sc-H and Cp2Sc-CH3

Cited by 172 publications

References 1 publication

Theoretical Studies on the Metathesis Processes, [Tp(PH3)MR(η2‐HCH3)] → [Tp(PH3)M(CH3)(η2‐HR)] (M=Fe, Ru, and Os; R=H and CH3)

Theoretical Studies on the Metathesis Processes, [Tp(PH3)MR(η2‐HCH3)] → [Tp(PH3)M(CH3)(η2‐HR)] (M=Fe, Ru, and Os; R=H and CH3)

CH Activation versus Yttrium–Methyl Cation Formation from [Y(AlMe4)3] Induced by Cyclic Polynitrogen Bases: Solvent and Substituent‐Size Effects

The σ‐CAM Mechanism: σ Complexes as the Basis of σ‐Bond Metathesis at Late‐Transition‐Metal Centers

Contact Info

Product

Resources

About

Theoretical Studies on the Metathesis Processes, [Tp(PH₃)MR(η²‐HCH₃)] → [Tp(PH₃)M(CH₃)(η²‐HR)] (M=Fe, Ru, and Os; R=H and CH₃)

Theoretical Studies on the Metathesis Processes, [Tp(PH₃)MR(η²‐HCH₃)] → [Tp(PH₃)M(CH₃)(η²‐HR)] (M=Fe, Ru, and Os; R=H and CH₃)

CH Activation versus Yttrium–Methyl Cation Formation from [Y(AlMe₄)₃] Induced by Cyclic Polynitrogen Bases: Solvent and Substituent‐Size Effects