Synthesis and characterization of diazine-ring containing hydrazones and their Zn(II) complexes

Two new zinc(II) coordination compounds have been synthesized by the reaction of diazine-ring containing Schiff bases di(2-pyridyl) ketone phthalazine-1-hydrazone (HzDPK) and di(2-pyridyl) ketone 3-chloropyridazine-6-hydrazone (HpDPK) with zinc(II) salts in acetonitrile in the presence of triethylamine. The crystal and molecular structures of the complexes and that of the ligand HpDPK were determined by single-crystal X-ray structure analysis. In both complexes, zinc atoms are situated in distorted octahedral environments, formed by two meridionally coordinated NNN tridentate, mono-deprotonated ligands. Since the applicability of the coordination compounds depends on their thermal properties, the thermal decomposition of the ligands and their complexes was followed by simultaneous TG–DSC measurements. The desolvation process of the complexes is rather slow as a consequence of a restricted diffusion through the lattice and finishes ~ 200 °C. The desolvated compounds are stable up to 340 °C. In order to follow the solvent evaporation and to have a better insight into the decomposition mechanism of the compounds coupled TG–MS measurements were carried out.