Binuclear Magnesium, Calcium, and Zinc Complexes Based on Nitrogen–Nitrogen‐Coupled Salicylaldiminate and β‐Diketiminate Ligands

Autor: Sven Range, Robert Stadler, Dirk F.-J. Piesik, Sjoerd Harder
Rok vydání: 2009
Předmět:
Zdroj: European Journal of Inorganic Chemistry. 2009:3569-3576
ISSN: 1099-0682
1434-1948
Popis: The diprotic bis(salicylaldimine) ligand N,N′-bis(3,5-di-tBu-salicylidene)diimine, (1-NN)H2, was smoothly deprotonated by reaction with two equivalents of a metal amide M[N(SiMe3)2]2 (M = Mg, Ca or Zn) to form a bimetallic metal amide complex (1-NN)[MN(SiMe3)2]2. This heteroleptic complex was only stable in the case of Mg and (1-NN)[MgN(SiMe3)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 C3-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-iPr-C6H3], which is abbreviated as (2-NN)H2, can be deprotonated only under much harsher reaction conditions. Attempted synthesis of (2-NN)[Mg(nBu)]2 gave after ligand exchange the homoleptic species (2-NN)Mg and Mg(nBu)2. For Ca, the complexes [(2-NN)Ca]2 and (2-NN)[CaN(SiMe3)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(SiMe3)2]2·(thf)2. Reaction of (2-NN)H2 with excess of Et2Zn gave the heteroleptic complex (2-NN)[ZnEt]2 and is stable towards ligand exchange reactions. The complex is not active in CO2/cyclohexene oxide copolymerization. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
Databáze: OpenAIRE
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