Influence of Temperature on Complex Formation of Metal with Aminophenanthridones

Color change of manganese(II), iron(III), cobalt(II), nickel(II), copper(II), chromium(III), and zinc(II) complexes with aminophenanthridones at 50-180°C is observed. The peculiarities of this effect, the reaction order, the reaction rate constant, and the activation energy are studied. Color change is explained by the rearrangement of the electronic structure of the complex and is assumed to be due to an increase in the contribution of the bipolar form of the ligand.