SYNTHESIS AND CRYSTAL STRUCTURE OF NEW OCTANUCLEAR COPPER(II) COMPLEX WITH BIS(5-CHLORO-2-HYDROXYBENZALDEHYDE) THIOCARBOHYDRAZONE

Abstract

The reaction of anhydrous copper(II) sulphate with 1,5-bis(5-chloro-2-hydroxybenzaldehyde) thiocarbohydrazone in dimethylformamide/ethanol (1:10), followed by re-crystallization of the product formed from DMSO, yielded the new octanuclear copper(II) complex. According to X-ray diffraction study the compound crystallizes in the triclinic space group P-1 and has the following composition [Cu8L4(DMSO)8]·8.75DMSO·2.5H2O. Each thiocarbohydrazone ligand adopts the thiol anti configuration providing two tridentate coordination sites, one with NNO, and the other with ONS donor atoms, able to accommodate two copper(II) ions. Thus, six of the seven donor atoms of a fully deprotonated ligand L4- are linked with two metal ions to give a dicopper(II) unit {Cu2L}0. The assembly of four such units into a metallomacrocyclic array takes place by coordination of the seventh donor atom of each {Cu2L} unit to the copper(II) atom of the adjacent unit which resides in the ONS ligand pocket to achieve a square-planar geometry. In the resulting architecture four copper(II) atoms are four-coordinate, with two ligands L4- filling all four coordination positions, while the other four copper(II) centers, each accommodated in an ONN ligand pocket, require additional two DMSO molecules to complete their coordination spheres (Fig. 1).figureFig.1 The structure of Cu8L4(DMSO)n.