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Stable Borocyclic Radicals via Frustrated Lewis Pair Hydrogenations
Lauren E Longobardi1,2, Lei Liu1,2, Stefan Grimme1,2
1Department of Chemistry, University of Toronto , 80 St. George Street, Toronto, Ontario M5S 3H6, Canada.
Abstract:
The synthesis and isolation of stable main group radicals remains an ongoing challenge. Here we report the application of frustrated Lewis pair chemistry to the synthesis of boron-containing radicals. H2 activation with polyaromatic diones and B(C6F5)3 leads to radical formation in good yields. These radicals are robust; they do not decompose on silica gel or react with O2 and are stable at 35 °C under N2 indefinitely. The mechanism of formation is explored experimentally, with support from DFT calculations. EPR and UV/vis spectroscopy as well as cyclic voltammetry data are provided, and the radicals are shown to react with cobaltocenes in one-electron chemical reductions to their corresponding borate anions.
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