Some heterobimetallic oxalate coordination precursors of lanthanum(III) of the type, M[La(CO)(HO)]· nHO (M = Mn(II), Co(II), Ni(II) and Cu(II)).

Heterobimetallic oxalato complex precursors, manganese(II)tetraaquatris(oxalato)lanthanate(III)hexahydrate (MnOLa), cobalt(II)pentaaquatris(oxalato)lanthanate(III)trihydrate (CoOLa), nickel(II)pentaaquatris(oxalato)lanthanate(III)hexahydrate (NiOLa) and copper(II)diaaquatris(oxalato)lanthanate(III)monohydrate (CuOLa) of the type, M[La(CO)(HO)]· nHO have been synthesized in aqueous medium. The precursors were characterized by elemental analysis, IR, electronic spectral and powder X-ray diffraction studies. The good crystalline nature with monoclinic structures predominates in MnOLa and NiOLa whereas triclinic structures were found in CoOLa and CuOLa. The solid-state thermal behaviour of the precursors was explored using TG, DTG and DTA in air. The MnOLa generated a mixture species consisting mainly of MnO, MnO, MnO, LaO and LaMnO at 1000 °C through the formation of several intermediate species at 380 and 570 °C. The studies revealed that CoOLa led mainly to LaCoO and LaCoO along with some oxides of both the cobalt and lanthanum at 1000 °C. In case of nickel analogue the mixture species identified at 1000 °C are mainly of LaNiO, LaO, NiO and NiO In case of CuOLa the product at 1000 °C consisted of LaCuO, LaCuO and oxides of copper and lanthanum. The nature of decomposition of the precursors in nitrogen were seen from DSC study and the kinetic parameters i.e., E, ln k, Δ H, Δ S and order of reaction of all the steps were evaluated and discussed. [ABSTRACT FROM AUTHOR]