Labile Base‐Stabilized Silyliumylidene Ions. Non‐Metallic Species Capable of Activating Multiple Small Molecules

Several base‐stabilized silyliumylidene ions (2 and 3) with different ligands were synthesized. Their behaviour appeared strongly dependent on the nature of ligand. Indeed, in contrast to the poorly reactive silyliumylidene ions 3 c,d stabilized by strongly donating ligands (DMAP, NHC), the silylene‐ and sulfide‐supported one (2‐H and 3 a) exhibits higher reactivity toward various small molecules. Furthermore, their capability to successively activate multiple small molecules was clearly demonstrated by processes involving successive reactions with silane/formamide, CO(2) and H(2). Moreover, HBPin adduct of 3 a (8‐C) catalyzes the hydroboration of pyridine. Of particular interest, silylene‐supported silyliumylidene complex 2‐H is one of the rare species able to activate two H(2) molecules.