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

Abstract

Herein we report stable silicon-boron radicals of composition LSi(NMe₂)–B(Br)Tip (1), LSi(NMe₂)–B(I)Tip (2) LSi(^tBu)–B(I)Tip (3) [L = PhC(N^tBu)₂]. They were prepared in high yield using a one pot reaction of LSiR, X₂BTip and KC₈ in a 1 : 1 : 1 molar ratio (R = ^tBu, NMe₂; X = Br, I). The reaction of the silicon–boron radical with Br₂ and Se affords the dihalogenated compound LSi(^tBu)–B(Br₂)Tip (4) and oxidative addition product LSi(^tBu)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.