Crystal structures of transition metal complexes with an asymmetrical tridentate Schiff-base ligand

Abstract

The asymmetrical tridentate Schiff base ( H 2L = (E)-N′-(2-hydroxybenzylidene)-4-hydroxybenzohydrazide) has been designed and synthesized. The four transition metal complexes with this ligand [Cu(HL)(NO 3)](H 2O) ( 1), [Zn 2(HL) 2(bipy)(H 2O) 2](NO 3) 2 ( 2), [Cu(HL)(H 2O)] 2(NO 3) 2 ( 3) and [Cu(HL)(Me 2NCO)] 2 ( 4) have been studied. The unsaturated coordination site of metal ion in complexes 1 and 2 is occupied by secondary ligand of nitrate and 4,4′-bipyridine. The crystal structure of complex 1 exhibits supramolecular framework with homochirality. Complexes 3 and 4 are dinuclear complexes bridged by the phenol oxygen atoms and the fifth coordination is occupied by H 2O molecular and DMF anion respectively. Hydrogen bonding and π–π stacking exist in all four complexes to construct supramolecular architecture.