Synthesis, structure and thermolysis of Ba(II)–M(II) (M = Co, Zn) bimetallic 3D-polymers as precursors of complex oxides

The Ba–Co and Ba–Zn heterometallic 3D-polymers [BaM(H2O)5(Me2mal)2]n, where Me2mal2− is the dimethylmalonic acid dianion, MII = Co (1), Zn (2), were synthesized by the reactions of CoSO4 or Zn(OAc)2, respectively, with Ba(OH)2 in water. The thermal dehydration of 1 and 2 occurs in one step. A kinetic model for the dehydration of complexes 1 and 2 is proposed. Crystalline BaCoO3−x and BaZnO2 were formed as a result of solid state thermolysis of 1 and 2 under the following conditions: air flow rate 60 ml/min, heating rate 10 °C/min up to t = 800 °C (1) or 750 °C (2), followed by storage for 12 h at the same temperatures.

The novel 3D-polymers [BaM(H2O)5(Me2mal)2]n (Me2mal2− – dimethylmalonic acid dianion) containing M (M = Co2+, Zn2+) and Ba in a 1:1 ratio were synthesized and characterized by X-ray analysis and a thermal study. It was established that crystalline BaCoO3−x and BaZnO2 were formed as the result of the solid state thermolysis of the porous 3D-polymers.Figure optionsDownload as PowerPoint slide