Frustrated Lewis Pair (FLP) Reactivity from Carbone-BPh3 Lewis Adduct.

We present a systematic investigation of the Frustrated Lewis Pair (FLP) chemistry of carbodicarbenes (fCDCs) featuring varied steric profiles in combination with strong (B(C6F5)3, BCF) and weak (BPh3) boron Lewis acids. The resulting CDC-borane systems display a full spectrum of behaviors: (i) tightly bound Lewis adducts lacking FLP reactivity, (ii) adducts exhibiting reversible dissociation and activate small molecules via FLP-type reactivity, and (iii) a "classical" FLP that remain unbound. The most reactive Lewis adduct, 1·BPh3, which exhibits the lowest dissociation energy, activates a broad range of bonds (C─H, O─H, N─H, H─B, H─Si, S─S, and CO2) and catalyzes hydroboration and hydrosilylation of ketones under mild, metal-free conditions. NMR exchange spectroscopy and DFT calculations reveal that its FLP reactivity originates from reversible dissociation and the formation of a reactive transient encounter complex. These findings establish carbone-based Lewis adducts as tunable platforms for FLP-type small molecule activation and main-group catalysis, where reactivity can be regulated through steric and electronic modulation.