Crystal chemistry of uranyl molybdates.: XI.: Crystal structures of Cs2[(UO2)(MoO4)2] and Cs2[(UO2)(MoO4)2](H2O)

Crystals of Cs-2[(UO2)(MoO4)(2)] have been synthesized by high-temperature solid-state reactions. The structure [orthorhombic, Pbca, a 11.762(2), b 14.081(2), c 14.323(2) angstrom, V 2372.3(6), Z = 8] was solved by direct methods and refined to R1 = 0.034 (wR2 = 0.044), calculated for 2577 unique observed reflections (vertical bar F-0 vertical bar >= 4 sigma(F)). Crystals Of Cs-2[(UO2)(MoO4)(2)](H2O) were prepared by hydrothermal reaction. The structure [monoclinic, P2(I)/c, a 8.2222(9), b 11.0993(l 0), c 13.9992(13) angstrom, beta 95.155(8)degrees, 111272.4(2) angstrom(3), Z = 4] was refined to R1 = 0.048 (wR2 = 0.099), calculated for 2487 unique observed reflections (vertical bar F-0 vertical bar >= 4 sigma(F)). The space group is P2(1)/c, in contrast to P 112(1) reported for this compound by Rastsvetaeva et al. (1999). The structures of C-s2[(UO2)(MoO4)(2)] and CS2[(UO2)(MoO4)(2)](H2O) both contain topologically identical sheets of corner-sharing UrO(5) pentagonal bipyramids and MoO4 tetrahedra with composition [(UO2)(MoO4)(2)](2-). The [(UO2)(MoO4)(2)](2-) sheets are oriented parallel to (001) in Cs-2[(UO2)(MoO4)(2)], and to (100) in Cs-2[(UO2)(MoO4)(2)](H2O). The sheets are linked by bonds to Cs+ cations located in the interlayer, and also by H bonds to H2O groups located in the interlayer in the case of Cs-2[(UO2)(MoO4)(2)](H2O). The [(UO2)(MoO4)(2)](2-) sheets in Cs-2[(UO2)(MoO4)(2)](H2O) are more distorted than those observed in Cs-2[(UO2)(MoO4)(2)].