3-Center-5-electron boryl radicals with σ(0)π(1) ground state electronic structure.

Five- and six-membered boron heterocycle-based three-center-five-electron (3c-5e) type boryl radicals with unusual σ(0)π(1) ground state electronic structures are predicted theoretically. Compared to σ(1)π(0) analogs, their unique electronic structure leads to both lower reactivity toward H-atoms and stronger coordination with Lewis bases. The corresponding Lewis base-stabilized four-center-seven-electron (4c-7e) type boryl radicals are even more unreactive toward H-atoms than the conventional 4c-7e ones.