Diketiminate Silicon(II) and Related NHSi Ligands Generated in the Coordination Sphere of Nickel(0)

The first silicon(II) hydroxide and related electronically tunable NHSi ligands have been synthesized in the coordination sphere of a [Ni(CO)(3)] moiety through facile addition of water and other electrophiles to the corresponding NHSi-tricarbonylnickel complex. The latter modified silicon (11) ligands are unique and exhibit striking donor/acceptor capabilities depending on their substitution pattern. While strong Lewis acids [H+ or B(C6F5)(3)] lead to modified silicon(II) ligands in the coordination sphere of nickel with an increased pi-acceptor and decreased sigma-donor character (PF3-like), by contrast, addition of water or trifluoromethanesulfonic acid furnishes the corresponding donor-stabilized silicon (II)-nickel complexes with a inverse donor/acceptor strength similar to those of triorganophosphines and NHCs.