Silyliumylidene Ion Stabilized by Two Σ-Donating Ni(0)- and Pd(0)-Fragments.

A silyliumylidene ion 2 stabilized by two sigma-donating Ni(0)- and Pd(0)-fragments was successfully synthesized. Due to the sigma-donation of M -> Si interactions, 2 presents a pyramidalized cationic silicon center with a localized lone pair. The additional coordination of basic Pd(0) fragment to the mono-Ni(0)-stabilized silyliumylidene 1 results in a higher HOMO level and an unchanged HOMO-LUMO gap and thus, 2 remains highly reactive. Interestingly, the coordination mode at the Si center is closely related to the nature of M-ligands. Indeed, the donor/donor-stabilized silyliumylidene ion 2 has been transformed into a donor/acceptor-stabilized ion 13, featuring a trigonal planar Si center with a vacant orbital, just via a ligand exchange reaction from PCy3/NHC toward PMe3. A silyliumylidene ion stabilized by two Ni(0)- and Pd(0)-based sigma-donating ligands was synthesized. Its particular coordination mode was characterized by a pyramidalized silicon center with a lone pair. Interestingly, a ligand exchange reaction leads to a significant change in the coordination mode to form a metal-based donor/acceptor-stabilized silyliumylidene ion, characterized by a vacant orbital at the Si center. Despite the stabilization by the two metal ligands, the silyliumylidene complex remains highly reactive. image