Ni(II) complexes with [N3O] Schiff base ligands bearing S-methylisothiosemicarbazide unit: design, synthesis and structure

Synthesis, structure and physico-chemical investigation of four new nickel(II) complexes with [N3O] chelate tetradentate ligands are described. They were obtained by template condensation of mono-S-methylisothiosemicarbazone of acetylacetone or 1-phenyl-butane1,3-dione with bifunctional carbonyl compounds such as anthranil aldehyde or 4-amino-3-penten-2-one. Square–planar complexes were obtained as only products with good yield and were fully characterised by EI MS, NMR (1H, 13C) spectroscopy, elemental analysis, and, in the case of three complexes, by X-ray investigation. A Cambridge Structural Database surveys on related square–planar Ni(II) complexes was also included, showing a small but significant correlation between NiO distances and ONiN angles.