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Z. Naturforsch. 2012,
67b, 987 – 994
doi:10.5560/ZNB.2012-0181
Reversible Heterolytic Si–H Bond Activation by an Intramolecular Frustrated Lewis Pair
1 Organisch-Chemisches Institut, Westfälische Wilhelms-Universität Münster, Corrensstraße 40, 48149 Münster, Germany
2 College of Chemistry & Materials Science, Northwest University, 229 North Taibai Road, Xi'an 710069, Shaanxi Province, P. R. China
3 Institut für Chemie, Technische Universität Berlin, Straße des 17. Juni 115, 10623 Berlin, Germany
Reprint requests to Prof. Dr. Gerhard Erker. Fax: +49 251 83 36503. E-mail:
erker@uni-muenster.de
Received July 3, 2012 / published online October 8, 2012
Dedicated to Professor Heribert Offermanns on the occasion of his 75th birthday
The intramolecular frustrated P/B Lewis pair Mes2PCH2CH2B(C6F5)2 (7) reacts readily with phenylsilane by heterolytic cleavage of the Si–H bond to give the zwitterion [Mes2(PhH2Si)P+CH2CH2B−H(C6F5)2] (8a), which has been fully characterized and its structure confirmed by X-ray crystal structure analysis. Variable-temperature NMR studies revealed that the reaction is reversible. Adduct 8a is the predominant species (ca. 98 %) in CD2Cl2 solution at low temperature (193 K), whereas at ambient temperature (299 K) it exists in
a ca. 7:3 equilibrium with unreacted 7 and PhSiH3. Diphenylsilane reacted similarly with the frustrated Lewis pair 7, however, the equilibrium was found to favor the starting materials in the investigated temperature range.
Key words: Frustrated Lewis Pairs, Silanes, Si–H Bond Activation, Silylphosphonium Ions
Supporting Material: