Syntheses, structures, and characterization of open-framework uranyl germanates

Inorg Chem. 2010 Aug 2;49(15):7123-8. doi: 10.1021/ic1010242.

Abstract

Three uranyl germanates, Cs(2)[(UO(2))(Ge(2)O(6))](H(2)O) (1), Ag[(UO(2))(2)(HGe(2)O(7))](H(2)O) (2), and Ag(2)[(UO(2))(3)(GeO(4))(2)](H(2)O)(2) (3) were synthesized under hydrothermal conditions, and their structures were determined by single crystal X-ray diffraction. Compound 1 crystallizes in space group P2(1)/n, a = 7.9159(2) A, b = 21.5949(5) A, c = 12.4659(3) A, beta = 96.964(1) degrees, V = 2115.24(9) A(3), Z = 8; 2 is orthorhombic Ama2, a = 7.124(1) A, b = 10.771(2) A, c = 14.024(1) A, V = 1076.2(4) A(3), Z = 4; 3 is orthorhombic Pnma, a = 10.0462(6) A, b = 7.4699(5) A, c = 17.776(1) A, V = 1334.0(2) A(3), Z = 4. These compounds are frameworks of uranyl square (1) or pentagonal (2, 3) bipyramids and four-membered rings of germanate tetrahedra (1), dimers of germanate tetrahedra (2), or chains of GeO(5) triangular bipyramids (3). There are channels through each of the frameworks that contain the low-valence cations and the H(2)O groups. Compound 1 dehydrates upon heating, but the framework remains intact to at least 900 degrees C.