Computational Study of the C−H Bond Activation in Ethylene on a Binuclear Ruthenium Complex

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• 作者：Samat Tussupbayev ; Sergei F. Vyboishchikov
• 刊名：Organometallics
• 出版年：2008
• 出版时间：August 11, 2008
• 年：2008
• 卷：27
• 期：15
• 页码：3681-3692
• 全文大小：648K
• 年卷期：v.27,no.15(August 11, 2008)
• ISSN：1520-6041

文摘

The reaction is substantially exothermicthe calculated total reaction enthalpy ΔH₂₉₈^° between 1 + 6C₂H₄ and 26 + 3C₂H₆ is about −90 kcal·mol⁻¹. The reaction occurs through a number of stages, each including ethylene coordination, at least two hydride migrations, and ethane elimination. The rate-determining step of the mechanism is the initial coordination of the first ethylene molecule to the reactant 1 to give the ethylene π complex (H)₂CpRu(μ-H)₂RuCp(η²-C₂H₄) (2). The free energy barrier is about 27 kcal·mol⁻¹ according to the static DFT calculations. Metadynamic simulations of the coordination process yield a ΔG₂₉₈ barrier of about 20 kcal·mol⁻¹. Another high-barrier step is the ethylene coordination to CpRu(η²:η¹-CHCH₂)₂RuCp (25) to give the final product 26. In total, the title reaction is a sophisticated multistep reaction with a large number of possible pathways. The mechanism of the reaction is largely determined by the flexibility of hydride ligands and by cooperation between both Ru centers.