Hydrosilane-Free Access to Iridium-NNSi Catalysts via Activation of Unstrained Si–C Bonds for C(sp3)–H Borylation

Abstract Hydrosilane-free access to iridium–silyl species is achieved via cleavage of unstrained Si–C bonds within pyridyl-based ligand scaffolds. Treatment of (triorganosilyl)methyl-substituted 2,2′-bipyridine and 1,10-phenanthroline ligands with a tris(boryl)iridium complex induces Si–C bond cleavage, affording organoboron compounds derived from the substituents on silicon. Not only methyl and phenyl groups but also ethyl substituents undergo efficient cleavage upon optimization of the ligand structure and reaction conditions. This strategy enables the generation of Ir/NNSi catalysts bearing less sterically demanding silyl groups, which exhibit high catalytic activity for the C(sp3)–H borylation at 80 °C. These findings establish Si–C bond activation as a practical platform for accessing metal–silyl species from stable precursors and provide a basis for the design of silyl-based ligands for catalytic C–H functionalization.