Transition-Metal-Free Cleavage of CO

Tertiary silane 1^H, 2-[(diphenylsilyl)methyl]-6-methylpyridine, reacts with tris(pentafluorophenyl)borane (BCF) to form the intramolecular pyridine-stabilized silylium 1⁺-HBCF. The corresponding 2-[(diphenylsilyl)methyl]pyridine, lacking the methyl-group on the pyridine ring, forms classic N(py)→B adduct 2^H-BCF featuring an intact silane Si−H fragment. Complex 1⁺-HBCF promotes cleavage of the C≡O triple bond in carbon monoxide with double C−C_sp2 bond formation, leading to complex 3 featuring a B-(diarylmethyl)-B-aryl-boryloxysilane fragment. Reaction with pinacol generates bis(pentafluorophenyl)methane 4 as isolable product, proving the transition-metal-free deoxygenation of carbon monoxide by this main-group system. Experimental data and DFT calculations support the existence of an equilibrium between the silylium–hydroborate ion pair and the silane–borane mixture that is responsible for the observed reactivity.