Syntheses and Characterization of (C2F5)3BCO and (C3F7)3BCO |
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| Authors: | Michael Gerken Prof. Dr. Gottfried Pawelke Dr. Eduard Bernhardt Dr. Helge Willner Prof. Dr. |
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| Affiliation: | 1. Bergische Universit?t Wuppertal, FB C‐ Anorganische Chemie, Gaussstrasse 20, 42097 Wuppertal (Germany);2. Permanent address: University of Lethbridge, Department of Chemistry and Biochemistry, Lethbridge, AB, T1K3M4 (Canada), Fax: (+1)?403‐329‐2057 |
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| Abstract: | The new tris(perfluoroalkyl)borane carbonyls, (C2F5)3BCO and (C3F7)3BCO, were prepared by means of a novel synthetic route using commercially available precursors by reacting K[(C2F5)3BCOOH] and K[(C3F7)3BCOOH] with concentrated sulfuric acid in the last step. The carboxylic acids, K[(C2F5)3BCOOH] and K[(C3F7)3BCOOH], were prepared by oxidative cleavage of the C?C triple bonds in Cs[(C2F5)3BC?CPh] and Cs[(C3F7)3BC?CPh] in a two‐step process to yield K[(C2F5)3BCO? COPh] and K[(C3F7)3BCO? COPh] as isolable intermediates. Crystal structures were obtained of K[(C2F5)3BCO? COPh], K[(C2F5)3BCOOH] ? H2O, (C2F5)3BCO, K[(C3F7)3BCOOH] ? 2 H2O, and (C3F7)3BCO. In the crystal structures of (C2F5)3BCO and (C3F7)3BCO the C?O bond lengths are 1.109(2) and 1.103(5) Å, respectively, which are among the shortest observed to date. Tris(pentafluoroethyl)borane carbonyl and (C3F7)3BCO slowly decompose at room temperature to yield CO, difluoroperfluoroalkylboranes and perfluoroalkenes. The decomposition of (C2F5)3BCO was found to follow a first‐order rate law with Ea=107 kJ mol?1. |
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| Keywords: | boranes carbonyl ligands structure elucidation vibrational spectroscopy |
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