Salicylaldimine Schiff bases – Generation of self-assembled and chiral complexes with Ni(II) and Zn(II) ions. An unusual antiferromagnetic interaction in a triply bridged Ni(II) dimer

Four new complexes of nickel(II) and zinc(II) with Schiff bases obtained from the condensation of salicylaldehyde and N,N-dimethyl-ethylene/propylenediamine and their reduced products have been synthesized and characterized by spectroscopic methods and single crystal X-ray structural analysis. Complex 1 is a six coordinated mononuclear complex of Ni(II), having a self assembled 2D structure with alternate cages and cavities running perpendicular to the c axis. The octagonal cavities are occupied by water molecules which are weakly hydrogen bonded to the eight oxygens lining the inner side of these cavities. Complex 2 is a phenoxo and aquo bridged dinuclear six coordinated complex of nickel(II) having two face sharing octahedra. Variable temperature magnetic susceptibility measurements of 2 show the presence of an antiferromagnetic coupling between the two nickel(II) centers. To the best of our knowledge it is the first dimeric complex of Ni(II), triply bridged by two phenoxo and one water molecule to show such a behavior. Complex 3 is a simple five coordinated monomer of Zn(II), whereas 4 is a chiral, dinuclear complex having zinc(II) ions with two different stereochemistries, which has been obtained by simultaneous resolution from achiral precursors.

Four new complexes of nickel(II) and zinc(II), with Schiff base ligands are reported. The mononuclear complex of Ni(II) 1 has self assembled 2D structure with octagonal cavities occupied by the H-bonded water molecules. Phenoxo and aquo bridged dinuclear six coordinated complex of nickel(II) 2 has antiferromagnetic coupling between the two nickel (II) centers. To the best of our knowledge it is the first dimeric complex of Ni(II), triply bridged by two phenoxo and one water molecule to show such a behavior. Complex 4 is a chiral, dinuclear complex having zinc(II) ions in two different stereochemistries, which has been obtained by simultaneous resolution from achiral precursors.Figure optionsDownload as PowerPoint slideHighlights
► Phenoxo/acetato bridged complexes of Ni(II) and Zn(II) are reported.
► A self assembled Ni(II) complex with cages and octagonal cavities.
► First triply bridged dimeric complex of Ni(II) showing antiferromagnetic coupling.
► A chiral, dinuclear complex with Zn(II) ions in two different stereochemistries.
► Chiral complex obtained by simultaneous resolution from achiral precursors.