Abstract
The diprotic bis(salicylaldimine) ligand N,N′‐bis(3,5‐di‐__t__Bu‐salicylidene)diimine, (1‐NN)H~2~, was smoothly deprotonated by reaction with two equivalents of a metal amide M[N(SiMe~3~)~2~]~2~ (M = Mg, Ca or Zn) to form a bimetallic metal amide complex (1‐NN)[MN(SiMe~3~)~2~]~2~. This heteroleptic complex was only stable in the case of Mg and (1‐NN)[MgN(SiMe~3~)~2~·thf]~2~ was structurally characterized by X‐ray diffraction. For Ca and Zn homoleptic products could be obtained: (1‐NN)Ca·(thf)~2~ and (1‐NN)Zn. The latter crystallized as a trimer with approximate C~3~‐symmetry. The diprotic N–N coupled bis(β‐diketimine) ligand [RHN–C(Me)=C–C(Me)=N–N=C(Me)–C=C(Me)–NHR, R = 2,6‐di‐__i__Pr‐C~6~H~3~], which is abbreviated as (2‐NN)H~2~, can be deprotonated only under much harsher reaction conditions. Attempted synthesis of (2‐NN)[Mg(__n__Bu)]~2~ gave after ligand exchange the homoleptic species (2‐NN)Mg and Mg(__n__Bu)~2~. For Ca, the complexes [(2‐NN)Ca]~2~ and (2‐NN)[CaN(SiMe~3~)~2~·thf]~2~ both have been prepared and structurally characterized by X‐ray diffraction. The latter heteroleptic complex is in benzene solution in equilibrium with [(2‐NN)Ca]~2~ and Ca[N(SiMe~3~)~2~]~2~·(thf)~2~. Reaction of (2‐NN)H~2~ with excess of Et~2~Zn gave the heteroleptic complex (2‐NN)[ZnEt]~2~ and is stable towards ligand exchange reactions. The complex is not active in CO~2~/cyclohexene oxide copolymerization. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)