Synthesis, characterization and crystal structures of dinuclear macrocyclic Schiff base copper(I) complexes bearing different bridges

Utilizing a new 20-membered macrocyclic Schiff base ligand with two coordination sites formed from the [2+2] condensation of 1,3-diaminopropane and benzene-1,3-dicarboxaldehyde in the presence of CuX (X = Cl−, Br−, I−) salts, air-stable dicopper(I) complexes were synthesized in acetonitrile, intramolecularly linked via two halide groups, and characterized by different physico-chemical techniques. The single crystal X-ray diffraction technique indicates these complexes consist of two N2X2 donor sets that have distorted tetrahedral coordination environments around the copper(I) ions. In these halogen-bridged binuclear Cu2LX2 systems the Cu⋯Cu separation can be controlled, as this distance is reduced on increasing the halide size and hence the X⋯X repulsion, with the rigidity of the macrocycle playing a significant role.

Graphical abstractThe synthesis, characterization and crystal structures of three dinuclear Cu(I) complexes of a 20-membered [2+2] macrocyclic, N4 donor, Schiff base ligand, containing different halogen bridges are described. The stacking and hydrogen bonds of the crystal structures and the role of bridging groups in controlling the Cu⋯Cu separation have been investigated.Figure optionsDownload full-size imageDownload as PowerPoint slide