[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][(UO2PO4)] was obtained by reaction at 800 degrees 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 P2(1)2(1)2(1) and unit-cell parameters a=6.9470(2) angstrom, b=7.0934(2) angstrom, c=25.7464(6) angstrom, V=1268.73(5) angstrom(3), 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 (2)(infinity)[(UO2)(VO4)](-) and double layers (2)(infinity)[(UO2)(V2O7)](+) connected through La-O bonds involving the uranyl oxygen of the uranyl-vanadate sheets. The double layers result from the connection of two (2)(infinity)[(UO2)(VO4)](-) 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. (C) 2011 Elsevier Inc. All rights reserved.