Self-assembly of copper(II) complexes with substituted aroylhydrazones and monodentate N-heterocycles: synthesis, structure and properties

Two ternary copper(II) complexes [Cu(L1)(py)] (1) and [Cu(L2)(Himdz] · CH3OH (2) with substituted aroylhydrazones, 5-bromo-salicylaldehyde-3,5-dimethoxy-benzoylhydrazone (H2L1) and 5-bromo-salicylaldehyde-p-methyl-benzoylhydrazone (H2L2), pyridine (py) and imidazole (Himdz), have been synthesized. Their crystal structures and spectroscopic properties have been studied. In each complex, the metal is in a square-planar N2O2 coordination formed by the phenolate-O, the imine-N and the deprotonated amide-O atoms of L2−, and the sp2 N atom of the neutral heterocycle. In the solid state, 1 exists as a centrosymmetric dimer due to very weak apical coordination of the metal bound phenolate-O. Complex 2 has no such apical coordination and exists as a monomer. Self-assembly via C–H ··· O, N–H ··· O and O–H ··· N interaction leads to a one-dimensional chain arrangement; other non-covalent interactions such as C–H ··· π and π ··· π are not involved.