[La(UO2)V2O7][(UO2)(VO4)] the first lanthanum uranyl-vanadate with structure built from two types of sheets based upon the uranophane anion-topology

The new lanthanum uranyl vanadate divanadate, [La(UO2)V2O7][(UO2)(VO4)] was obtained by reaction at 800 °C between lanthanum chloride, uranium oxide (U3O8) and vanadium oxide (V2O5) and the structure was determined from single-crystal X-ray diffraction data. This compound crystallizes in the orthorhombic system with space group P 212121 and unit-cell parameters a =6.9470(2) Å, b =7.0934(2) Å, c =25.7464(6) Å, V =1268.73(5) Å3, Z =4. A full matrix least-squares refinement yielded R 1=0.0219 for 5493 independent reflections. The crystal structure is characterized by the stacking of uranophane-type sheets View the MathML source[(UO2)(VO4)]−∞2 and double layers View the MathML source[La(UO2)(V2O7)]+∞2 connected through La–O bonds involving the uranyl oxygen of the uranyl-vanadate sheets. The double layers result from the connection of two View the MathML source[La(UO2)(VO4)2]−∞2 sheets derived from the uranophane anion-topology by replacing half of the uranyl ions by lanthanum atoms and connected through the formation of divanadate entities.