The crystal structure of a double oxalate of yttrium and ammonium, NH4Y(C2O4)2.H2O

Crystal Structure and Thermal Behavior of La(H2O)2M(C2O4)2·H2O (M=K, NH4) Studied by Powder X-Ray Diffraction

“…A relevant explanation of this feature is the exchange of two-thirds of both the ammonium cations and the water molecules, located in the interlayer spacing of the structure of La(H O) (NH )(C O ) ) H O, by the transuranium cations. From the layered-type structures of the compounds of this oxalate family, namely, the isostructural lanthanum potassium oxalate, yttrium sodium oxalate (10), and yttrium ammonium oxalate (28), it can be suggested that similar ion-exchange properties could also be expected. Finally, the study of the thermal decomposition of the two phases, carried out with temperature-dependent X-ray powder diffraction, has clearly pointed out the unexpected existence of crystalline anhydrous LaK (C O ) and La(NH )(C O ) .…”

The thermal characteristics of potassium oxalato lanthanates: K3LnOx3 · n H2O (Ln=La−Tb) and K8Ln2Ox7 · 14 H2O (Ln=Tb−Yb, Y)

“…The reason why Ln2Ox 3 and MLnOx2 (M = alkaline metal) would not form more bonds like the complexes studied here is that there are no unbridged oxalate ligands in those compounds to facilitate the process. All oxalate anions in those compounds are rigidly bonded in an extensive bridging structure [16][17][18][19][20]. Actually even in the compounds K3LnOx 3 where each Ln3+ cation is bridged to two other Ln 3 § cations via oxalate ligands, structural rigidity (more pronounced in complexes of smaller Ln 3+) appears to impose restrictions on the degree of new Ln-O contacts which is reflected in the diminishing magnitude of AH (Fig.…”

“…X-ray structure determination reveals that the complexes K3LnOx 3 9 3 H 2) have chains with ... Ox(LnOx 2 9 OH2)Ox... units while the K 8 Ln2Ox 7 9 14 H20 have dinuclear species Ox3LnOxLnOx38- [1]. The formation of these new bonds will lead to at least coordination number nine around the Ln3+ and there are no steric or radii ratio restrictions which make this possibility unlikely since nonacoordination is known in many room temperature structures of Ln3Ox 3 9 n H20 and LnOx~-systems [16][17][18][19][20]. The reason why Ln2Ox 3 and MLnOx2 (M = alkaline metal) would not form more bonds like the complexes studied here is that there are no unbridged oxalate ligands in those compounds to facilitate the process.…”

New open-framework three-dimensional lanthanide oxalates containing as a template the diprotonated 1,2- or 1,3-diaminopropane

“…Except for the three-dimensional (3D), [{Er(H 2 O) 3 } 2 (C 2 O 4 ) 3 ] Á 12H 2 O, whose the structure was solved recently [20], these oxalates present a layered honey-comb open-architecture, whether they are decahydrates or hexahydrates [21][22][23][24]. Mixed oxalates, lanthanide-alkaline element (including ammonium), are either bi-dimensional [25][26][27][28][29] or tri-dimensional [30,31].…”