Pd(II) Complexes with Nitrogen-oxygen Donor Ligands: Synthesis, Characterization and Catalytic Activity for Suzuki-Miyaura Cross-coupling Reaction

Schiff base ligands are considered ‘privileged ligands’ and are attractive because they are easily prepared by the condensation between aldehyde/ketone and imines both of which are relatively cheap and easily available. Stereogenic centres or other elements of chirality such as planes and axes can be introduced in the synthetic design (Cozzi 2004) as well as benzene rings containing electron donating or withdrawing substituents. The mono, di, triand multi-dentate chelating Schiff base ligands can be designed according to the binding environments of metal ions. The metal complexes of chiral Schiff base ligands showed stereoselectivity in organic transformation, hence the synthesis of chiral complexes become an important area of current research in co-ordination chemistry (Gupta & Sutar 2008). Schiff base ligands are able to co-ordinate many different metals (Osman 2006; Sallam 2006) and to stabilize them in various oxidation states. The Schiff base complexes have been used in catalytic reactions (Dhara et al. 2010; Tamizh & Karvembu 2012) and as models for biological systems (Singh et al. 2012; Mohamed et al. 2010). Many Schiff base complexes show excellent catalytic activity in various reactions at high temperature (>100°C) and in the presence of moisture (Gupta & Sutar 2008).