Thermal behavior of the coordination compound [Co(urea)6](NO3)

The coordination compound [Co(urea)(6)](NO3)(2) was synthesized and physico-chemically characterized. The thermal decomposition carried out in dynamic air and inert atmosphere under nonisothermal conditions has been investigated by means of combined thermogravimetry/ mass spectrometry, X-ray diffraction, IR and UV-VIS spectroscopy as well as magnetic measurements. The course of the thermal decomposition starts with two-phase transitions ( melting and a O-h --> T-d configuration change of the Co2+ ion) and continues with seven mass loss steps. According to the thermogravimetric and magnetic investigations a dimeric compound, [Co(biuret)(NCO)](2)(NO3)(2), is assumed to arise. Up similar to 250 degreesC, an oxohydroxide nitrate intermediate is formed and a gradual oxidation of the Co2+ ions is observed. At 550 degreesC, Co3O4 with mean crystallite sizes of similar to 150 Angstrom is identified.