SYNTHESIS, CRYSTAL STRUCTURE AND THIRD-ORDER NONLINEAR OPTICAL PROPERTIES OF COPPER(II) COMPLEXES WITH SCHIFF-BASE LIGAND DERIVATIVES FROM DITHIOCARBAZATE

Abstract

The synthesis and spectroscopic characterization of D-M-D type neutral Cu(II) chelates with Schiff base ligands, R‒C6H4CHNNHCSSCH3 (R = ‒N(CH3)2, ‒CH3O) are reported. Spectroscopic data suggest that the Schiff base ligands act as single negatively charged bidentate ligands forming stable neutral metal complexes. Single crystal X-ray structure determinations of the Cu(II) chelates established that the coordination geometry of Cu(II) is square planar with two equivalent Cu-N and Cu-S bonds. The Schiff base ligands lost a proton from their tautomeric thiol form and coordinated to Cu(II) via the mercapto sulfur and β-nitrogen as expected. The two phenyl rings and the coordination moieties are almost in one plane forming an extensive electronic delocalization system. Magnetic properties and ESR data support the square-planar coordination geometry for both of the Cu(II) chelates. Nonlinear optical properties were measured using z-scan methods in CH3CN solution.