Synthesis and characterization of novel thiosemicarbazone ligands and their metal complexes

In this study; firstly, bis(thiosemicarbazone) ligands were synthesized by the condensation reaction of thiosemicarbazide and various ketone compounds. The synthesized ligands were; 2-(2-(4-methoxyphenyl)hydrazono)cyclohexane-1,3-dione bis(thiosemicarbazone) (L1), 2-(2-(3-bromophenyl)hydrazono)-5,5-dimethylcyclohexane-1,3-dione bis(thiosemicarbazone) (L2), 2-(2-(4-methoxyphenyl)hydrazono)-5,5-dimethyl cyclohexane-1,3-dione bis(thiosemicarbazone) (L3) and 2-(2-(3-bromophenyl)hydrazono)cyclohexane-1,3-dione bis(thiosemicarbazone) (L4). The metal complexes were synthesized by the reaction of obtained ligands (L1, L2, L3 and L4) with CuCl2.2H2O, NiCl2.6H2O, CoCl2.6H2O, ZnCl2.2H2O and MnCl2.4H2O salts. The structures of synthesized ligands and their complexes were characterized using elemental analysis, IR, UV-Vis., 1H-NMR spectra, 13C-NMR spectra, magnetic susceptibility, liquid cromatography-mass spectrum (LC-MS), thermogravimetry analysis-differential thermal analysis (TGA-DTA), and differantial scanning calorimetry techniques. Square-planar geometry was suggested for the Cu(II) and Co(II) complexeses of L1, whereas octahedral geometry was suggested for the Ni(II) and Mn(II) complexes. The suggested structures for the L2 complexes; Cu(II), Ni(II), Co(II) and Mn(II) complexes were octahedral, while Zn(II) complex was tetrahedral. Cu(II) complex of L3 ligand was square-planar, whereas Ni(II) and Co(III) complexes were octahedral and Zn(II) complex was tetrahedaral. Then suggested geometries for the L4 complexes; Cu(II) complex was square-planar, Ni(II), Co(II) and Mn(II) complexes were octahedral, while Zn(II) complex was tetrahedral. It was thaught that, the cobalt complex of L3 exhibits low-spin octahedral geometry, due to it was diamagnetic.