On the Synthesis of a T‐Shaped Imido Nickel Complex and Trigonal Amido Nickel Complexes

Abstract

AbstractThe synthesis of a T‐shaped imido nickel complex is reported, obtained by the reaction of phenyl azide with the linear nickel(I) silylamide complex K{18‐crown‐6}[NiL2] (L=−N(Dipp)SiMe3; Dipp=2,6‐diisopropylphenyl). In addition, an unusual shift of a SiMe3 unit from an ancillary ligand to a putative [Ni=NPh] complex is observed. Examination of the resulting [Ni=NDipp] complex for its electronic properties leads to its description as a low‐spin nickel(III) imide and revealed only limited activity with respect to H‐atom abstraction from C−H bonds or nitrene. Attempts to obtain information about the general features of trigonal nickel(II) amide products, that would result from such a H‐atom abstraction reaction, via reaction of linear nickel(II) silylamide [NiL2] with alkali metal salts of primary amides revealed the reduction to the linear nickel(I) complex K{18‐crown‐6}[NiL2]. The same is observed for alkoxides, secondary amides or benzyl. Reaction of the organic salts with the anionic nickel(II) complex NBu4[NiBrL2] under salt elimination also give the linear nickel(I) complex. Partial formation of an otherwise stable T‐shaped nickel(II) can be observed only for the electron‐poor diphenyl amide. This implicates that reduction of the starting nickel(II) complexes by different organic alkali metal salts likely does not occur via a homolytic Ni−R bond cleavage but a direct SET process from the unligated substrate to the nickel(II) ion.