Germylide-Catalyzed Hydrosilylation and Hydroboration: Insertion/Metathesis versus Non-hydride Mechanisms

Reaction of cyclic germylene NacNac′Ge (3, where NacNac′ = [ArNC(Me)CHC(═CH2)NAr]2– and Ar = 2,6-Pri2C6H3) with KOBut affords new germyl anion [NacNac′Ge(OBut)]−K+, which can be further converted into hydridogermylide [NacNac′Ge(H)]−K+ (8). Anionic compound 8 catalyzes hydrosilylation of ketones and aldehydes and hydroboration of N-heterocycles. Mechanistic studies show that these reactions proceed by a non-hydride mechanism in which the germylide serves as an activator for the reducing reagent, silane or borane.