Single-Electron Transfer Reactions in Frustrated and Conventional Silylium Ion/Phosphane Lewis Pairs
M. Sc. Anastasia Merk
Institut für Chemie, Carl von Ossietzky Universität Oldenburg, Carl von Ossietzky-Strasse 9–11, 26129 Oldenburg, Germany
Search for more papers by this authorDr. Henning Großekappenberg
Institut für Chemie, Carl von Ossietzky Universität Oldenburg, Carl von Ossietzky-Strasse 9–11, 26129 Oldenburg, Germany
Search for more papers by this authorDr. Marc Schmidtmann
Institut für Chemie, Carl von Ossietzky Universität Oldenburg, Carl von Ossietzky-Strasse 9–11, 26129 Oldenburg, Germany
Search for more papers by this authorM. Sc. Marcel-Philip Luecke
Institut für Chemie, Technische Universität Berlin, Strasse des 17. Juni 115, 10623 Berlin, Germany
Search for more papers by this authorM. Sc. Christian Lorent
Institut für Chemie, Technische Universität Berlin, Strasse des 17. Juni 115, 10623 Berlin, Germany
Search for more papers by this authorProf. Dr. Matthias Driess
Institut für Chemie, Technische Universität Berlin, Strasse des 17. Juni 115, 10623 Berlin, Germany
Search for more papers by this authorProf. Dr. Martin Oestreich
Institut für Chemie, Technische Universität Berlin, Strasse des 17. Juni 115, 10623 Berlin, Germany
Search for more papers by this authorCorresponding Author
Dr. Hendrik F. T. Klare
Institut für Chemie, Technische Universität Berlin, Strasse des 17. Juni 115, 10623 Berlin, Germany
Search for more papers by this authorCorresponding Author
Prof. Dr. Thomas Müller
Institut für Chemie, Carl von Ossietzky Universität Oldenburg, Carl von Ossietzky-Strasse 9–11, 26129 Oldenburg, Germany
Search for more papers by this authorM. Sc. Anastasia Merk
Institut für Chemie, Carl von Ossietzky Universität Oldenburg, Carl von Ossietzky-Strasse 9–11, 26129 Oldenburg, Germany
Search for more papers by this authorDr. Henning Großekappenberg
Institut für Chemie, Carl von Ossietzky Universität Oldenburg, Carl von Ossietzky-Strasse 9–11, 26129 Oldenburg, Germany
Search for more papers by this authorDr. Marc Schmidtmann
Institut für Chemie, Carl von Ossietzky Universität Oldenburg, Carl von Ossietzky-Strasse 9–11, 26129 Oldenburg, Germany
Search for more papers by this authorM. Sc. Marcel-Philip Luecke
Institut für Chemie, Technische Universität Berlin, Strasse des 17. Juni 115, 10623 Berlin, Germany
Search for more papers by this authorM. Sc. Christian Lorent
Institut für Chemie, Technische Universität Berlin, Strasse des 17. Juni 115, 10623 Berlin, Germany
Search for more papers by this authorProf. Dr. Matthias Driess
Institut für Chemie, Technische Universität Berlin, Strasse des 17. Juni 115, 10623 Berlin, Germany
Search for more papers by this authorProf. Dr. Martin Oestreich
Institut für Chemie, Technische Universität Berlin, Strasse des 17. Juni 115, 10623 Berlin, Germany
Search for more papers by this authorCorresponding Author
Dr. Hendrik F. T. Klare
Institut für Chemie, Technische Universität Berlin, Strasse des 17. Juni 115, 10623 Berlin, Germany
Search for more papers by this authorCorresponding Author
Prof. Dr. Thomas Müller
Institut für Chemie, Carl von Ossietzky Universität Oldenburg, Carl von Ossietzky-Strasse 9–11, 26129 Oldenburg, Germany
Search for more papers by this authorDedicated to Professor Werner Uhl on the occasion of his 65th birthday
Graphical Abstract
An electron against frustration! Silylium ions accept an electron from sterically hindered triarylphosphanes, regardless of whether these Lewis acids form a frustrated or a classical Lewis pair with the phosphane Lewis base. The thus-generated phosphoniumyl radical cations were characterized by EPR and UV/Vis absorption spectroscopy and single-crystal X-ray diffraction (see picture).
Abstract
Silylium ions undergo a single-electron reduction with phosphanes, leading to transient silyl radicals and the corresponding stable phosphoniumyl radical cations. As supported by DFT calculations, phosphanes with electron-rich 2,6-disubstituted aryl groups are sufficiently strong reductants to facilitate this single-electron transfer (SET). Frustration as found in kinetically stabilized triarylsilylium ion/phosphane Lewis pairs is not essential, and silylphosphonium ions, which are generated by conventional Lewis adduct formation of solvent-stabilized trialkylsilylium ions and phosphanes, engage in the same radical mechanism. The trityl cation, a Lewis acid with a higher electron affinity, even oxidizes trialkylphosphanes, such as tBu3P, which does not react with either B(C6F5)3 or silylium ions.
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