Proton conduction of the La(III)M(III) compounds, LaM(ox)3·10H2O (abbreviated to LaM; M = Cr, Co, Ru, La; ox(2-) = oxalate) is studied in view of their networks. LaCr and LaCo have a ladder structure, and the ladders are woven to form a channel network. LaRu and LaLa have a honeycomb sheet structure, and the sheets are combined to form a layer network. The occurrence of these structures is explained by the rigidness versus flexibility of [M(ox)3](3-) in the framework with large La(III). The channel networks of LaCr and LaCo show a remarkably high proton conductivity, in the range from 1 × 10(-6) to 1 × 10(-5) S cm(-1) over 40-95% relative humidity (RH) at 298 K, whereas the layer networks of LaCr and LaCo show a lower proton conductivity, ∼3 × 10(-8) S cm(-1) (40-95% RH, 298 K). Activation energy measurements demonstrate that the channels filled with water molecules serve as efficient pathways for proton transport. LaCo was gradually converted to La(III)Co(II)(ox)2.5·4H2O, which had no channel structure and exhibited a low proton conductivity of less than 1 × 10(-10) S cm(-1). The conduction-network correlation of LaCo(ox)2.5·4H2O is reported.

Proton Conduction Study on Water Confined in Channel or Layer Networks of LaIIIMIII(ox)3·10H2O (M = Cr, Co, Ru, La)

The thermal decomposition of metal complexes—XVII: Potassium tris(oxalato)manganate(III) trihydrate

The solid-state photochemical dissociation of potassium tris(oxalato) ferrate (III) 3-hydrate

Synthesis and the thermal decomposition of iron(III) tris(oxalato) ferrate(III) tetrahydrate

Cobalt(II) bis(oxalato)cobaltate(II) tetrahydrate (Co[Co(C2O4)] · 4H2O) was synthesized and characterized on the basis of elemental and spectral analysis. The thermal decomposition of the complex was investigated in air and nitrogen media. In air, complete dehydration of the complex occured at 251°, followed by rapid decomposition to a mixture of CO2O3 and Co3O4 at 300°; in nitrogen, dehydration occurred at 206°, followed by decomposition to a mixture of Co and CoC2O4, and finally to Co + CoO, at 394° and 420°, respectively. The activation energies for the dehydration and decomposition reactions in nitrogen and air media were evaluated and a tentative reaction mechanism for the thermal decomposition of the complex was proposed.

https://link.springer.com/content/pdf/10.1023/A:1010168609780.pdf

W.W. Wendlandt

Papers

The thermal decomposition of metal complexes—XVI: Potassium tris(oxalato)cobaltate (III) trihydrate