Complicated electronic process of C-C σ-bond activation of cyclopropene by ruthenium and iridium complexes: Theoretical study

Atsushi Ishikawa, Yudai Tanimura, Yoshihide Nakao, Hirofumi Sato, Shigeyoshi Sakaki

研究成果: Article査読

5 被引用数 (Scopus)

抄録

C-C σ-bond activation of cyclopropene by RuCl2(PPh 3)2 and IrCl(CO)(PMe3)2 was theoretically investigated. The activation barrier and the reaction energy calculated here indicate that the reaction occurs more easily by the ruthenium complex than by the iridium complex, which is consistent with the experimental results that the Ru-vinylcarbene species is formed but the Ir-vinylcarbene is not. The valence bond analysis of the CASSCF wave function disclosed that the Ir-vinylcarbene bond is significantly weaker than that of the Ru complex because the d6 square pyramidal complex of Ru is more favorable than the d8 complex of Ir for this bonding interaction. In both the Ru and Ir systems, a precursor complex is formed by coordination of the C 1=C2 double bond of cyclopropene with the metal center, where C1 and C2 are sp2 carbons and C 3 is an sp3 carbon. In the transition state, one C-C single bond (named C1-C3) is almost broken, but the M-C1 bond (M = Ru or Ir) and another C-C single bond (named C 2-C3) are becoming stronger. When moving from the transition state to a metal-vinylcarbene product, the C1=C 2 double bond changes to the C1-C2 single bond with the concomitant change of the C2-C3 single bond to the C2=C3 double bond. To induce these bond formation and bond breaking processes, the valence state of the metal center must change in the reaction. The promotion energy to the valence state becomes smaller in the ruthenium reaction system when going from the reactant to the product but becomes considerably larger in the iridium reaction system. This is the reason that the C-C σ-bond cleavage of cyclopropene occurs more easily in the ruthenium complex than in the iridium complex. The difference in promotion energy between the ruthenium and iridium systems is reasonably interpreted in terms of d-d orbital splitting by ligand-field and d electron number.

本文言語English
ページ(範囲)8189-8199
ページ数11
ジャーナルOrganometallics
31
23
DOI
出版ステータスPublished - 2012 12 10
外部発表はい

ASJC Scopus subject areas

  • 有機化学
  • 物理化学および理論化学
  • 無機化学

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