bis(nicotinamide) and bis(N,N-diethyl nicotinamide) p-hydroxybenzoate complexes of Ni(II), Cu(II) and Zn(II) -: Spectrothermal studies

The mixed-ligand p-hydroxybenzoate complexes of Ni(II), Cu(II) and Zn(II) with nicotinamide and N, N-diethylnicotinamide were synthesized and characterized by elemental analysis, magnetic susceptibility measurements and mass spectrometry. The thermal behavior of the complexes was studied by simultaneous TG, DTG and DTA methods in static air atmosphere. The infrared spectral characteristics of the complexes are also discussed. The complexes contain two water molecules, two p-hydroxybenzoato (p-hba) and two nicotinamide (na) (or diethylnicotinamide (dena)) ligands per formula unit. In these complexes, all ligands are coordinated to the metal ion as monodendate ligands. In Zn(II)-na and Cu(II)-dena complexes, the p-hydroxybenzoate behaves as bidentate chelating ligand through carboxylic oxygen atoms. The decomposition pathways and the stability of the complexes are interpreted in the terms of the structural data. The final decomposition products were found to be the respective metal oxides.