The architecture of dinuclear Ni and Cu complexes: twisted and parallel forms controlled by the self-assembly of Schiff base ligands

Novel dinuclear complexes were synthesized through the self-assembly of macrocyclic Schiff base ligands and either nickel(II) or copper(II) ions. X-Ray structural analysis revealed that the complexes had either a double helix (twisted) structure in which each atom had a distorted square-planar coordination or a non-helical (parallel) structure in which the metals had octahedral coordination. The helical complexes were rather unusual in that their helicity originated not in the coordination centre, but mainly in the linker moieties in the ligand. Several factors influencing the formation of the helical structure are discussed.