Mixed Schiff Base and 8-hydroxyquinoline Complexes with Manganese, Iron and Zinc– Synthesis, Characterization and Properties

Mixed complex ions of Mn (II), Fe (II) and Zn (II), with Schiff base (L) as primary ligand and 8-hydroxyquinoline as a secondary ligand were prepared, in which the condensation of acetophenone and 2- aminophenol was employed for the production of Schiff base. The Schiff base ligand was a lustrous brown crystalline solid with a melting temperature of 240 ℃ that was obtained in a low yield of 36.21%. The metal complexes were produced as solids with dark to deep brown colors that stable to oxidation and decomposed at 310 ℃ to 340 ℃. The complexes’ molar conductance in dimethylformamide (DMF) was determined to range between 3.11 and 4.15 Ω−1cm2mol−1, indicating that they are non-electrolytic in nature. The presence of 11/2 uncoordinated water molecules was detected during the crystallization process in Manganese and iron complexes, while 2 was predicted for the Zn (II) complex. According to the IR- spectrum data, Schiff base ligand does lose the phenolic hydrogen during complexation and is bidentately coordinated to the metal ions by phenolic oxygen (deprotonated) and imine nitrogen (HC = N-) as monobasic ligand. Similar to this, hydroxyquinone coordinated using quinoline nitrogen and deprotonated phenolic oxygen. Data from the experiment suggested that the mixed ligand may be expressed as [ML (HQ)] nH2O with square planar geometry in the four coordinates.