Inorganic Chemistry, Vol.45, No.25, 10207-10214, 2006
New layered uranium phosphate fluorides: Syntheses, structures, characterizations, and ion-exchange properties of A(UO2)F(HPO4)center dot xH(2)O (A = Cs+, Rb+, K+; x=0-1)
Single crystals of three new layered uranium phosphate fluorides, A(UO2)F(HPO4)center dot xH(2)O(A = Cs+, Rb+, and K+; x = 0-1) have been synthesized by hydrothermal reactions using UO3, H3PO4, HF, and corresponding alkali metal halides as reagents. Although all three new materials have layered structures, each of them contains different structural motifs within the layer. While Cs(UO2)F(HPO4)center dot 0.5H(2)O and Rb(UO2)F(HPO4) reveal noncentrosymmetric crystal structures, K(UO2)F(HPO4)center dot H2O crystallizes in a centrosymmetric space group. In addition, the ion-exchanged phases for all three materials are highly crystalline. Crystal data: Cs(UO2)F(HPO4)center dot 0.5H(2)O, orthorhombic, space group Pca2(1) (No. 29), with a = 25.656(5) angstrom, b = 6.0394(12) angstrom, c = 9.2072(18) angstrom, and Z = 4; Rb(UO2)F(HPO4), orthorhombic, space group Cmc2(1) (No. 36), with a = 17.719(4) angstrom, b = 6.8771(14) angstrom, c = 12.139(2) angstrom, and Z = 8; K(UO2)F(HPO4)center dot H2O, monoclinic, P2(1)/n (No. 14), with a = 6.7885(14) angstrom, b = 8.7024(17) angstrom, c = 12.020(2) angstrom, beta = 94.09(3)degrees, and Z = 4.