Studies on the structure and thermal behaviour of the Mn—urea complex

The urea complex of manganese was synthesized and its structure established to be [Mn(Urea)(H₂O)₃Cl₂] from elemental analyses, IR and UV and visible spectroscopy and magnetic susceptibility measurements. The thermal behaviour has been studied by thermogravimetry (TG) in nitrogen and air atmospheres and differential thermal analysis (DTA) in air. TG analysis shows three main steps of decomposition leading to oxide formation in the final stage when the complex is heated in air, and MnCl₂ formation when it is heated in nitrogen. The kinetics of decomposition of the complex have been studied. Plots of the Coats—Redfern equation show two breaks from which three values of the activation energy are reported. From the results, it is concluded that decomposition of the complex is a heterogeneous process.