On the thermal decompositions of the trivalent trioxalato complexes of Al,Cr, Mn, Fe and Co

The thermal decompositions of the complexes K-3[M(ox)(3)]. 3H(2)O (M=Al, Cr , Mn, Fe, Co; ox=C2O42-) were studied. Dehydration of the complexes occurs up to 200 degreesC, this being a three-step process for M=Al, Cr, Mn and Co , and a two-step process for M=Fe. Decomposition of the dehydrated complexe s proceeds in several steps. For M=Al, Cr and Fe, the decomposition takes p lace with the evolution of CO, whereas for M=Mn and Co the decomposition of the oxalate ligand yields solid C besides CO. The temperature of CO libera tion decreases in the series Cr < Al < Co < Mn < Fe. For M=transition metal , this trend can be explained by the fact that the strength of the C-C bond in the oxalate ligand decreases in the series Cr < Co < Mn < Fe.