Thermal studies of some mixed complexes of Mn(II) with picrate and nitrogen donors

The thermal decompositions of nine mixed ligand complexes of Mn(II) containing picrate and mono- or bidentate nitrogen ligands were studied by thermogravimetry. The kinetics of decomposition were examined by using the Coats-Redfern and Horowitz-Metzger equations; the decomposition was in all cases of the first order. The activation energies and other kinetic parameters were computed. The decomposition mechanisms exhibited a similar character for all the studied compounds. It was observed from the TG curves that the complexes decomposed to give six-coordinate intermediates, formed from substitution of the picrate into the inner coordination sphere. These intermediates decomposed to Mn(II) picrate and finally to Mn₂O₃.