Aldehyde Hydrosilylation with Ethylzinc Complexes of Bulky <i>β</i> ‐Thioketiminate Ligands

The synthesis of a novel β ‐thioketiminate ligand, H‐SacNac Ar* ( 3 ), featuring a bulky 2,6‐bis(benzhydryl)‐4‐methylphenyl substituent, and its zinc ethyl complex [(SacNac Ar* )ZnEt] ( 4 ), is reported. Complex 4 catalyzes the hydrosilylation of benzaldehyde with PhSiH 3 , showing enhanced activity relative to the less bulky analogue [(SacNac Dipp )ZnEt] 2 , particularly upon addition of MeOH as an activator. Under these conditions, 4 exhibits high selectivity toward dialkoxysilane product ( B), over monoalkoxysilane ( A ) or trialkoxysilane ( C ) products. Density functional theory calculations support a mechanism involving precatalyst activation by MeOH to form a zinc alkoxide intermediate, followed by σ ‐bond metathesis with PhSiH 3 affording a catalytically active zinc hydride complex. The results highlight the role of ligand sterics and alcohol activators in tuning catalytic activity and offer insights into the design of new zinc‐based hydrosilylation catalysts.