Differential Thermal and Thermogravimetric Studies of Carbonatodiphenanthrolinecobalt(III) Complexes

The CoPhen₂CO₃]X ·nH₂O complexes, where Phen, phenanthroline; X · nH₂O = Cl · 5H₂O, Br · 4H₂O, I · 4H₂O, NCS · 3H₂O, NO₂ · 5H₂O, NO₃ · 3H₂O, ClO₄, and ClO₃, are studied by the differential thermal and thermogravimetric methods. After the endoeffect of complete dehydration of the complexes, the DTA curves exhibit effects of the ^III reduction to ^II by the outer-sphere chloride, bromide, and iodide anions. In the case of the outer-sphere nitrite anion, the endoeffect of the reduction of ^III with the nitrito group is followed by the exoeffect of oxidation of the organic ligand with the nitrogen dioxide formed. In the case of the outer-sphere chlorate and perchlorate anions, the complexes are decomposed at temperatures of 250 and 310°, respectively, without preliminary ^III reduction.