Reduction of a diamidocarbene-supported borenium cation: isolation of a neutral boryl-substituted radical and a carbene-stabilized aminoborylene

We have synthesized the first diamidocarbene (DAC)-supported borenium salt, [3][OTf], which was found to readily undergo two sequential 1-electron reductions. The first reduction forms a thermally robust, crystalline boryl-substituted DAC-centred radical (3(center dot)) which has been fully characterized by XRD, EPR spectroscopy, and DFT analyses. The 1-electron reduction of 3(center dot) resulted in the formation of a DAC-supported aminoborylene, 4, which has been characterized computationally and by multinuclear NMR spectroscopy.