Cu(II) complexes with asymmetrical [N3O] Schiff-base ligands derived from S-methylisothiosemicarbazide.

Two new square-planar Cu(II) complexes with [N3O] chelate tetradentate ligands were synthesized and characterized by elemental analysis, EI MS, UV-vis and ESR spectroscopy, and magnetic measurements. They were obtained by template condensation of mono-S-methylisothiosemicarbazone of acetylacetone or 1-phenyl-butane-1,3-dione with anthranil aldehyde. One of two title complexes crystallizes in two forms, monoclinic and orthorhombic. Both of them were analysed by X-ray diffraction and significant differences concerning the distortion from planarity of the coordination environment were observed. Their structure was also compared with that of the Ni complex having the same tetradentate ligands, using previously reported data. Small but significant differences between the coordination complexes of the two metals were observed in the bond distances and angles of the central core.