Persistent and Predominantly Localized Boron Radical from the Reduction of a Three-Dimensional Analogue of NHC-Stabilized Borafluorenium

In this contribution, we reported the three-dimensional (3D) analogues of N-heterocyclic carbene (NHC)-stabilized 9-borafluorenium and 9-borafluorene radical. The radical was fully characterized by cyclic voltammetry (CV), UV-Vis absorption spectroscopy, electron paramagnetic resonance (EPR) and single-crystal X-ray diffraction analyses. The distinct boron-centered radical character of 9-borafluorene radical was corroborated by DFT calculations and EPR analysis.