Synthesis, thermal study and some properties of N2O4-donor Schiff base and its Mn(III), Co(II), Ni(II), Cu(II) and Zn(II) complexes

The new hexadentate N2O4 Schiff base ligand from condensation of 2,4-hydroxybenzophenone and 1,3-propanediamine has been prepared in methanol and ethanol solutions. The Schiff base synthesized from EtOH contains half molecule of amine per one molecule of ligand in its structure. The complexes were synthesized from the direct reaction of this ligand and Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) acetates. The Schiff base and its complexes were characterized by elemental analysis, X-ray crystallographic techniques, spectroscopic (UV-Vis, IR) and thermal (TG, TG-FTIR) methods, molar conductance and magnetic measurements. The complexes, except for Ni(II) compound, similar to the Schiff base are amorphous solids. The Ni(II) complex crystallizes in the monoclinic space group P2(1)/c. The N2O2 coordination geometry around nickel(II) is slightly tetrahedrally distorted square planar. Variable temperature magnetic studies of the paramagnetic complexes show the existence of weak antiferromagnetic [for complexes of manganese(III) and cobalt(II)] and weak ferromagnetic [for copper(II)] interactions. The complexes are stable at ambient temperature. After heating at first they lose solvent molecules (water or methanol), and after that organic part undergoes defragmentation and combustion. Based on the obtained data from the TG-FTIR analysis, the main gaseous products resulting from thermal degradation in nitrogen atmosphere are CO2, CO, NH3, acetic acid, methane, C6H6, C6H5CN and C6H5CH3.