Thermal decomposition of tetrakisoxalatouranates(IV) of mixed metals: characterisation of a new potassium uranate phase

[NH4][(CH3)2NH2]2[Ta(C2O4)4]·2H2O: the first (oxalato)tantalate(V) complex structurally characterized

“…The search has been limited to the mononuclear species where the oxalate ligand does not bridge two metal atoms. The tetra(oxalato)uranate(IV) complexes [8,9] has also been removed from this search because it was found that U IV atom usually binds an additional water molecule into its coordination sphere [8]. In a simultaneous TG and DTA analysis of 1 (Fig.…”

“…Also, the oxalate anion is often a bridging ligand in construction of homo-or heterometallic compounds with open-framework architectures [1] and interesting magnetic and optical properties [2]. The tetra(oxalato)metalates [M(C 2 O 4 ) 4 ] n-(M = Zr IV [3,4], Hf IV [3,5], Nb IV [6,7], U IV [8,9], Yb III [10]) involve transition metals in higher oxidation states and with higher coordination numbers. The [M(C 2 O 4 ) 4 ] nanion is often used as a base-building unit [11] for the formation of several types of homo/heterometallic supramolecular (3D) nano-porous architectures with zeolitic properties, where the central metal atom adopts dodecahedral (DD) or square-antiprismatic (SA) coordination [12,13].…”

Flux Growth of [NaK6F][(UO2)3(Si2O7)2] and [KK6Cl][(UO2)3(Si2O7)2]: The Effect of Surface Area to Volume Ratios on Reaction Products

“…For the synthesis of [NaK 6 F]­[(UO 2 ) 3 (Si 2 O 7 ) 2 ], this reaction yielded thick yellow rod crystals of [NaK 6 F]­[(UO 2 ) 3 (Si 2 O 7 ) 2 ], Figure (left), in approximately 50% yield along with some large orange polyhedral crystals of K 2 UO 4 . For the synthesis of [KK 6 Cl]­[(UO 2 ) 3 (Si 2 O 7 ) 2 ], this reaction resulted in thin yellow rods of [KK 6 Cl]­[(UO 2 ) 3 (Si 2 O 7 ) 2 ], Figure (right), in approximately 40% yield along with a small amount (<5% of product) of silver metal.…”

An investigation on the solid-state thermal decomposition behaviour of uranyl(II)diaquatris(oxalato)lanthanate(III)octahydrate and cobalt(II)uranyl(II)pentaquatris(oxalato)lanthanate(III)octahydrate

“…Thermal decomposition of the compounds led mainly the mixture of Ln 2 O 2 CO 3 and UO 2+x as intermediates in the range 625-655 K which reacted above 975 K forming mixed oxide with a fluorite structure. Mixed metal compounds, K 2 MU(C 2 O 4 ) 4 Á8H 2 O (M = Ca 2+ or Cd 2+ ) [6] and KLnU(C 2 O 4 ) 4 Á8H 2 O (Ln = La 3+ , Ce 3+ , Pr 3+ , Nd 3+ or Tb 3+ ) [7] at 1075 K were found to give a new mixed oxide phases with pervoskite related cubic structure, and a mixture of K 2 U 2 O 7 and (Ln, U)O 2 AE x , respectively. The respective lithium and sodium uranyl oxalate hydrate, Li 2 UO 2 (C 2 O 4 ) 2 Á5H 2 O and Na 2 UO 2 (-C 2 O 4 ) 2 Á4H 2 O were found [8] to belong to a monoclinic system, and they decomposes to monouranates through the formation of alkali metal carbonates and UO 2 as intermediates.…”