a Synthetic Route to Mixed Ligand Schiff Base Complexes

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Aug 15, 2010 - chemistry, biochemistry and inorganic chemistry[1-7]. ..... [27] Cotton, F.; Wilkinson, G., "Advanced Inorganic Chemistry", 5th Ed., John Wiley and ...

JJC

Jordan Journal of Chemistry Vol. 5 No.4, 2010, pp. 349-361

 

Transimination; a Synthetic Route to Mixed Ligand Schiff Base Complexes a b a Fatima Esmadi *, Tareq Irshaidat and Osama Hamadneh

a b

Department of Chemistry, Yarmouk University, Irbid – Jordan Department of Chemistry, Al-Hussein Bin Talal University, Ma'an – Jordan

Received on April 26, 2010

Accepted on Aug. 15, 2010

Abstract Copper and nickel Schiff base complexes have been prepared and reacted with aqueous ammonia and some amines. A variety of Schiff bases have been chosen, two bidentate Schiff bases; HSN and HNPY which are N-(2-hydroxy-1-naphthalidine)-3-aminopyridine and Nsalicylidinenaphthylamine, respectively, three tridentate Schiff bases; HBN, HPN and HBS which are N-2-hydroxynaphthalidine-2-aminobenzoic acid, N-2-hydroxynaphtalidine-2-aminophenol and N-salicylidne-2-aminobenzoic acid, respectively, and one tetradentate Schiff base which is N,N-(salicylidine)-4,5-dimethylphenylendiamine (H2Sal2Me2Ph). The complexes derived from the bidentate and the tetradentate Schiff bases; [M(NPY)2], [M(SN)2] and [M(Sal2Me2Ph)] (M= Cu and Ni), undergo transimination reaction with a complete loss of the exchanged amine from the coordination sphere. However, in case of the tridentate Schiff base complexes, M(PN), M(BN), M(BS), amine exchange took place and the eliminated amine gets bonded to the metal, which produced new type of mixed Schiff base complexes.

Keywords: Cu(II) and Ni(II) Schiff base complexes; Transimination; Mixed schiff base complexes.

Introduction Schiff bases and their relevant metal ion complexes find interest in organic chemistry, biochemistry and inorganic chemistry[1-7]. Schiff base formation involves a two-step reaction between the carbonyl compound and the amino compound[8,9]. Metal ions contribute to the formation of Schiff bases by creating stable complexes, thus producing a favorable overall free energy of reaction[10]. Furthermore, the metals were found to catalyze these reactions by serving as a reaction template[11]. It is known that upon coordination to metal ligand properties change sufficiently to make possible a reaction pathway that would otherwise not take place. Numerous studies have established that imines, particularly when present in cationic form > C = N+