Computational Study of C−C Coupling on Diruthenium Bis(μ-vinyl) Ethylene π-Complex

Abstract

We have performed a computational study of the C−C coupling reaction between coordinated ethylene and two vinyl ligands in the binuclear bis(vinyl)-ethylene complex CpRu(η2-C2H4)(μ-η1:η2-CHCH2)2RuCp (1) to yield the ruthenacyclopentadiene complex CpRu(η2-C2H4)(CMeCH-CHCMe)RuCp (28), described by Suzuki et al. This reaction is a sophisticated multistep process with a large number of possible pathways. Agostic interactions and the cooperativity of both Ru centers play a crucial role in the mechanism of the reaction. Our calculations provide support for Suzuki et al.’s proposal that the conversion of the reactant 1 to the final product 28 proceeds through the intermediate Cp(H)Ru(μ-H)(CMeCH-CHCMe)RuCp (20). However, the pathway originally proposed by Suzuki et al. leading to the intermediate 20 is unfavorable (Δ⧧ G°298 = 33 kcal·mol−1). We found a new, more favorable pathway with a Δ⧧ G°298 of 20 kcal·mol−1. The rate-determining step of the mechanism is ethylene coordination to the intermediate CpRu(μ-H)(CHMeCH-CHCMe)RuCp (22). The free energy barrier is about 29 and 24 kcal·mol−1 at the BP86 and MPWLYP1M level, correspondingly.

Synthesis, Characterization, and Reactions of Ruthenium(II), -(III), and -(IV) Complexes with Sterically Demanding 1,2,4-Tri-tert-butylcyclopentadienyl Ligands

“…Along with the reaction paths, vacant sites were generated at the metal centers via the hydrogenation of the coordinated ethylene and subsequent liberation of ethane. The reaction mechanism has been elucidated in detail by theoretical calculations using DFT …”

Vinylidene carbonylation at a manganese–iron complex: A density functional study of mechanism

“…Previous quantum chemistry studies of vinylidene polynuclear complexes addressed only homoatomic species. The RueRu vinylidene species [(C 5 H 5 )Ru] 2 (m-C]CH 2 )H(m-h 1 :h 2 eCH]CH 2 )(h 2 eC 2 H 4 ) and [(C 5 H 5 ) Ru] 2 (m-C]CH 2 )(meCHeCH 3 )(h 2 eC 2 H 4 ) were explored as the products of CeH bond cleavage in a vinyl CH]CH 2 ligand [8]. Another theoretical study considered ReeRe species [9].…”