Triflate-Enabled Rhodium-Catalyzed Cross-Dehydrogenative Si-N Bond Formation from Hydrosiloxanes

Hydrosiloxanes are an attractive yet underexplored class of silicon reagents for Si-N bond formation, largely due to challenges associated with their activation. Herein, we demonstrate that the triflate anion plays a non-inonnocent role in catalysis by promoting substrate organization and N-H activation. Rhodium complexes of the type [Rh(H)(X)(κ²-NSi^DMQ)(PCy₃)] (NSi^DMQ = {4,8-dimethylquinolin-2-yloxy}dimethylsilyl; X = Cl, OTf), featuring an organosilyl ligand, display marked anion-dependent reactivity in the cross-dehydrogenative coupling (CDC) of secondary amines with hydrosiloxanes. Whereas the chloride complex is catalytically inactive, the triflate derivative efficiently promotes Si-N bond formation. Among the hydrosiloxanes investigated, HSiMe(OSiMe₃)₂ proved to be the most versatile reagent. Combined experimental and computational studies reveal an unconventional pathway in which hydrosiloxanes coordinate to the metal center through the oxygen atom rather than via the Si-H bond. This reactivity is enabled by the hemilability of the NSi^DMQ ligand, which undergoes hemidissociation to generate the active species. The triflate ligand facilitates N-H bond activation by organizing the amine through hydrogen-bonding interactions, thereby promoting Si-N bond formation. The interplay between anion effects and ligand hemilability provides valuable insight for the design of catalytic systems for Si-N bond formation from challenging substrates such as hydrosiloxanes.