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(NtBu)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)[double bond, length as m-dash]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.