TY - JOUR

T1 - Chiral open-framework uranyl molybdates. 2. Flexibility of the U:Mo = 6:7 frameworks

T2 - Syntheses and crystal structures of (UO(2)) (0.82)[C(8)H(20)N](0.36)[(UO (2))(6)(MoO(4))(7)(H(2)O) (2)](H(2)O)(n) and [C(6)(H)(14)N (2)][(UO(2))(6)(MoO(4))(7)(H (2)O)(2)](H(2(O)(m)

AU - Krivovichev, Sergey V.

AU - Burns, Peter C.

AU - Armbruster, Th

AU - Nazarchuk, Evgeniy V.

AU - Depmeier, Wulf

PY - 2005/3/1

Y1 - 2005/3/1

N2 - Two new chiral open-framework uranyl molybdates, (UO2) 0.82[C8H20N]0.36[(UO 2)6(MoO4)7(H2O) 2](H2O)n (1) and [C6H 14N2][(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(MoO 4)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.

AB - Two new chiral open-framework uranyl molybdates, (UO2) 0.82[C8H20N]0.36[(UO 2)6(MoO4)7(H2O) 2](H2O)n (1) and [C6H 14N2][(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(MoO 4)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.

KW - Chiral

KW - Crystal structure

KW - Flexibility

KW - Open framework

KW - Uranyl molybdates

UR - http://www.scopus.com/inward/record.url?scp=13444256311&partnerID=8YFLogxK

U2 - 10.1016/j.micromeso.2004.10.019

DO - 10.1016/j.micromeso.2004.10.019

M3 - Article

AN - SCOPUS:13444256311

VL - 78

SP - 217

EP - 224

JO - Zeolites

JF - Zeolites

SN - 1387-1811

IS - 2-3

ER -