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Evidence for a Rapid Degenerate Hetero‐Cope‐Type Rearrangement in [Cp*W(S)2S‐CH2‐CHCH2] |
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| Authors: | Florian Eweiner Shunsuke Senda Klaus Bergander Dr. Christian Mück‐Lichtenfeld Dr. Stefan Grimme Prof. Dr. Roland Fröhlich Dr. Michiko Aoyama Hiroyuki Kawaguchi Prof. Dr. Yasuhiro Ohki Dr. Tsuyoshi Matsumoto Dr. Gerald Kehr Dr. Kazuyuki Tatsumi Prof. Dr. Gerhard Erker Prof. Dr. |
| Affiliation: | 1. Organisch‐Chemisches Institut, Westf?lische Wilhelms Universit?t Münster, Corrensstra?e 40,D‐48149 Münster (Germany), Fax: (+49)?251‐83‐36503;2. Department of Chemistry, Faculty of Science, Nagoya University, Furo‐cho, Chikusa‐ku, Nagoya 464‐8602 (Japan);3. NMR analysis;4. Quantum chemical calculations;5. X‐ray crystal structure analysis |
| Abstract: | Treatment of the salt [PPh4]+[Cp*W(S)3]? ( 6 ) with allyl bromide gave the neutral complex [Cp*W(S)2S‐CH2‐CH?CH2] ( 7 ). The product 7 was characterized by an X‐ray crystal structure analysis. Complex 7 features dynamic NMR spectra that indicate a rapid allyl automerization process. From the analysis of the temperature‐dependent NMR spectra a Gibbs activation energy of ΔG≠ (278 K)≈13.7±0.1 kcal mol?1 was obtained [ΔH≠≈10.4±0.1 kcal mol?1; ΔS≠≈?11.4 cal mol?1 K?1]. The DFT calculation identified an energetically unfavorable four‐membered transition state of the “forbidden” reaction and a favorable six‐membered transition state of the “Cope‐type” allyl rearrangement process at this transition‐metal complex core. |
| Keywords: | allyl ligands automerization density functional calculations fluxionality tungsten |