Coordination and supramolecular aspects of the metal complexes of chiral N-salicyl-β-amino alcohol Schiff base ligands: Towards understanding the roles of weak interactions in their catalytic reactions

Abstract

Chiral N-salicyl-β-amino alcohol Schiff bases are important ligands widely employed in asymmetric catalysis. These are referred to as 'tridentate salen ligands' and are considered as a member of the well-known 'privileged ligands' group. The desire to understand the roles of weak non-covalent interactions in catalysis has greatly expanded the scope of structural studies on catalytic complexes. This review focuses on the structural and supramolecular features of the metal complexes derived from chiral N-salicyl-β-amino alcohol Schiff base ligands. Metal complexes of varying nuclearities, such as, mono-, di-, tri- and tetra-nuclear complexes, have been reported from this group of ligands. The geometries of the metal centers present in these complexes vary from tetrahedral, square-planar, square-pyramidal, octahedral to trigonal prismatic. The available structural data clearly indicate the coordination versatility of this group of ligands towards various metal ions. In addition, these complexes exhibit a variety of weak bonding interactions leading to the formation of supramolecular structures such as helices, 1-D chains, 3-D networks, etc. in solid state. The articles discussed here highlight the competence of chiral N-salicyl-β-amino alcohol Schiff base ligands to support various structural and supramolecular features in their complexes, but the role of these features in determining their catalytic efficiencies have not yet been studied in detail. We believe that the present review may inspire many such studies in future. © 2013 Elsevier B.V.