Excellent yield of a variety of silicon-boron radicals and their reactivity

Herein we report stable silicon-boron radicals of composition LSi(NMe2)-B(Br)Tip (1), LSi(NMe2)-B(I)Tip (2) LSi(Bu-t)-B(I)Tip (3) [L = PhC((NBu)-Bu-t)(2)]. They were prepared in high yield using a one pot reaction of LSiR, X(2)BTip and KC8 in a 1:1:1 molar ratio (R = Bu-t, NMe2; X = Br, I). The reaction of the silicon-boron radical with Br-2 and Se affords the dihalogenated compound LSi(Bu-t)-B(Br-2)Tip (4) and oxidative addition product LSi(Bu-t)=Se (5). All the compounds were characterized by single-crystal X-ray structural analysis, electron paramagnetic resonance (EPR) analysis, elemental analysis, multinuclear NMR spectroscopy, and mass spectrometry. Quantum chemical calculations show that the B-centered radicals 1-3 are stabilised by hyperconjugative interactions.