Brunner, Henri and Muschiol, Manfred and Tsuno, Takashi and Takahashi, Takemoto and Zabel, Manfred (2010) Pyramidal Stability of 16-Electron Half-Sandwich Intermediates [CpRu(P-P)](+) with P-P Ligands Forming Four- to Six-Membered Chelate Rings. ORGANOMETALLICS, 29 (2). pp. 428-435. ISSN 0276-7333,
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This paper reports the synthesis, isomer separation, and X-ray characterization of the compounds (S-Ru,S-C)-/(R-Ru,S-C)-[CpRu(Chairphos)Cl], Chairphos = (S)-1,3-bis(diphenylphosphanyl)butane, and cis-/trans-[CpRu(Dppm-Me)Cl], Dppm-Me = 1,1-bis(diphenylphosphanyl)ethane. The Cl/I exchange reactions proceeded with predominant retention of the metal configuration, accompanied by some inversion, except for tans-[CpRu(Dppm-Mc)Cl], which was stercospecifically converted to trans-[CpRu(Dppm-Mc)I]. Temperature-dependent kinetic measurements afforded rates and activation parameters of the Cl/I exchange and epimerization reactions that follow basilica-type energy profiles. Dissociation of Cl- from [CpR-u(Chairphos)Cl] and [CpRu(Dppm-Mc)Cl] gives pyramidal intermediates [CpRu(Chairphos)](+) and [CpRu(Dppm-Me)](+), which maintain the metal configuration. The 16-electron intermediates can react with excess I- to form the iodo complexes with retention of the metal configuration, or they can change the metal configuration by pyramidal inversion, leading to formation of iodo complexes with inverted metal configuration. The kinetic measurements show that the pyramidal inversion via planar transition states depends on the P-Ru-P' angles. It increases with decreasing chelate ring size, because small P-Ru-P' angles resist planarization in the transition, which requires larger P-Ru-P' angles.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | BITE-ANGLE DIPHOSPHINES; COMPLEXES; |
| Subjects: | 500 Science > 540 Chemistry & allied sciences |
| Divisions: | Chemistry and Pharmacy > Institut für Anorganische Chemie > Alumni or Retired Professors > Prof. Dr. Henri Brunner |
| Depositing User: | Dr. Gernot Deinzer |
| Date Deposited: | 10 Aug 2020 07:54 |
| Last Modified: | 10 Aug 2020 07:54 |
| URI: | https://pred.uni-regensburg.de/id/eprint/25289 |
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