Metal-free Catalytic Hydrogenolysis of Chlorosilanes into Hydrosilanes with “Inverse” Frustrated Lewis Pairs

The challenging metal-free catalytic hydrogenolysis of silyl chlorides to hydrosilanes is unlocked by using an inverse frustrated Lewis pair (FLP), combining a mild Lewis acid (Cy2BCl) and a strong phosphazene base (BTPP), in mild conditions (10 bar of H2, r.t.). In the presence of a stoichiometric amount of the base, the hydrosilanes R3SiH (R = Me, Et, Ph) are generated in moderate to high yields (up to 95%) from their chlorinated counterparts. A selective formation of the valuable difunctional monohydride Me2SiHCl is also obtained from Me2SiCl2. A mechanism is proposed based on stoichiometric experiments and DFT calculations; it highlights the key role of borohydride species, generated by the heterolytic splitting of H2.