Mode of Activation of Cobalt(II) Amides for Catalytic Hydrosilylation of Alkenes with Tertiary Silanes

Cobalt­(II)
complexes capable of catalyzing alkene hydrosilylation
in the absence of external activators are rarely known, and their
activation mode has remained poorly understood. We present here that
cobalt­(II) amide complexes, [Co­(N­(SiMe3)2)2] and its NHC adducts [(NHC)­Co­(N­(SiMe3)2)2] (NHC = N-heterocyclic carbene), are
effective catalysts for the hydrosilylation of alkenes with tertiary
silanes. Mechanistic studies revealed that cobalt­(II) amides can react
with hydrosilane to form cobalt­(I) species, silylamide, and hydrogen,
which serves as the entry to the genuine catalytically active species,
presumably cobalt­(I) species, for the cobalt-catalyzed hydrosilylation
reaction.