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.