Chiral open-framework uranyl molybdates. 2. Flexibility of the U:Mo = 6:7 frameworks: syntheses and crystal structures of (UO2)0.82[C8H20N]0.36[(UO2)6(MoO4)7(H2O)2](H2O)n and [C6H14N2][(UO2)6(MoO4)7(H2O)2](H2O)m

Two new chiral open-framework uranyl molybdates, (UO2)0.82[C8H20N]0.36[(UO2)6(MoO4)7(H2O)2](H2O)n (1) and [C6H14N2][(UO2)6(MoO4)7(H2O)2](H2O)m (2) have been synthesized by hydrothermal methods. The structures of 1 and 2 have been refined using X-ray diffraction data collected at −127 °C. The structure of 1 [orthorhombic, C2221, a = 12.2303(15), b = 18.966(2), c = 22.392(3) Å, V = 5194.0(11) Å3] has been refined to R1 = 0.043 on the basis of 4126 unique observed reflections. The structure of 2 [orthorhombic, C2221, a = 11.3256(15), b = 19.860(3), c = 23.731(3) Å, V = 5337.8(12) Å3] has been refined to R1 = 0.056 on the basis of 3519 unique observed reflections. The structures of 1 and 2 are based upon complex chiral [(UO2)6(MoO4)7(H2O)2] frameworks of corner-sharing UO7 bipyramids and MoO4 tetrahedra. In addition to framework U sites, the structure of 1 contains an additional, partially-occupied and disordered U(4) site, located within the framework cavities and coordinated by several disordered anions to form the complex [(UO2)(H2O)5]2+ cation. The structure of 2 contains disordered DABCO (1,4-diazabicyclo[2.2.2]-octane) molecules. The geometrical parameters of the uranyl molybdate frameworks in the structures of 1 and 2 are significantly different. The a parameter of 1 is about 0.9 Å longer than that of 2, whereas the b and c parameters of 1 are shorter than those of 2 (∼0.9 and 1.3 Å, respectively). This occurs due to the adaptation of the [(UO2)6(MoO4)7(H2O)2]2− framework to the shape of the complex [(UO2)(H2O)5]2+ cation in 1. Analysis of the U-O-Mo bond angles of the frameworks indicates the U-O(15)-Mo and U-O(20)-Mo links are the most flexible. The transition from 2 to 1 involves an increase of the U-O(15)-Mo and U-O(20)-Mo angles from 146.7° to 169.0° and from 151° to 171°, respectively.