Evidence for extensive single-electron-transfer chemistry in boryl anions: isolation and reactivity of a neutral borole radical.
Despite the synthesis of a boryl anion by Yamashita et al. in 2006, compounds that show boron-centered nucleophilicity are still rare and sought-after synthetic goals. A number of such boryl anions have since been prepared, two of which were reported to react with methyl iodide in apparent nucleophilic substitution reactions. One of these, a borolyl anion based on the borole framework, has now been found to display single-electron-transfer (SET) reactivity in its reaction with triorganotetrel halides, which was confirmed by the isolation of the first neutral borole-based radical. The radical was characterized by elemental analysis, single-crystal X-ray crystallography, and EPR spectroscopy, and has implications for the understanding of boron-based nucleophilic behavior and the emergent role of boron radicals in synthesis. This radical reactivity was also exploited in the synthesis of compounds with rare B-Sn and B-Pb bonds, the latter of which was the first isolated and structurally characterized compound with a "noncluster" B-Pb bond.
Institut für Anorganische Chemie, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg (Germany) http://www-anorganik.chemie.uni-wuerzburg.de/Braunschweig/
Rüdiger
R
Bertermann
Holger
H
Braunschweig
Rian D
RD
Dewhurst
Christian
C
Hörl
Thomas
T
Kramer
Ivo
I
Krummenacher
Lewis bases; anions; boroles; boron; radicals