Mixed ligand complexes of coumarilic acid/nicotinamide with transition metal complexes

Coumarilate–nicotinamide complexes of Co^II and Zn^II were synthesized and investigated by elemental analysis, magnetic susceptibility, solid state UV–Vis, direct injection probe mass spectra, FTIR spectra, thermoanalytic TG-DTG/DTA, and crystal X-ray diffraction methods. It was obtained that both complex structures contain 2 mol aqua ligands, 2 mol coumarilate (CCA^?) and 2 mol nicotinamide (NA) ligands per formula unit. The CCA^? and NA ligands were bonded to metal cations as monodentate through acidic oxygen and nitrogen of pyridine ring, respectively. Thermal decomposition of each complex starts with dehydration and continue removing of 1 mol NA ligand. The thermal dehydration of the complexes takes place in one or two steps. The decomposition mechanism and thermal stability of the investigated complexes are interpreted in terms of their structures. The final decomposition products are found to be metal oxides.