Spectrothermal studies on Co(II), Ni(II), Cu(II) and Zn(II) salicylato (1,10-phenanthroline) complexes

The cobalt, nickel, copper and zinc atoms in bis(1,10-phenanthroline)bis(salicylato-O)metal(II) monomeric octahedral complexes [M(Hsal)(2)(phen)(2)].nH(2)O, (M:Co(II), n=1; Cu(II), n=1.5 and Ni(II), Zn(II), n=2) are coordinated by the salicylato monoanion (Hsal) through the carboxyl oxygen in a monodentate fashion and by the 1,10-phenanthroline ( phen) molecule through the two amine nitrogen atoms in a bidentate chelating manner. On the basis of the DTG(max), the thermal stability of the hydrated complexes follows order: Ni(II) (149degreesC)>Co(II) (134degreesC)>Zn(II) (132degreesC)>Cu(II) (68degreesC) in static air atmosphere. In the second stage, the pyrolysis of the anhydrous complexes takes place. The third stage of decomposition is associated with a strong exothermic oxidation process (DTA curves: 410, 453, 500 and 450degreesC for the Co( II), Ni( II), Cu( II) and Zn( II) complexes, respectively). The final decomposition products, namely CoO, NiO, CuO and ZnO, were identified by IR spectroscopy.