Hydrothermal synthesis and characterization of [(UO2)(2)F-8(H2O)(2)Zn-2(4,4 '-bpy)(2)]center dot(4,4 '-bpy), a mixed-metal uranyl aquofluoride with a pillared layer structure

摘要

A mixed-metal uranyl aquofluoride, [(UO2)(2)F-8(H2O)(2)Zn-2(4,4'-bpy)(2)](.)(4,4'-bpy), has been synthesized under hydrothermal conditions and has been structurally characterized by single-crystal X-ray diffraction, infrared spectroscopy, thermogravimetric analysis, emission spectroscopy, and solid-state NMR spectroscopy. It is one of the few uranium fluoride-organic framework solids in which an organic molecule is directly incorporated into the extended structure of the metal fluoride and is the first example of mixed-metal uranium oxyfluoride incorporating an organic ligand. The structure consists of neutral layers of edge- and corner-sharing uranium-centered pentagonal bipyramids and zinc-centered octahedra, which are linked through 4,4'-bpy ligands into a 3-D framework. The H-1 MAS NMR spectrum is in support of the conclusion that the occluded 4,4'-bpy molecules in the structural channels are not protonated. Crystal data: monoclinic, space group P2(1)/c, a = 9.4630(5) angstrom, b = 22.384(l) angstrom, c = 16.7534(8) angstrom,beta 91.899(2)degrees, V = 3546.7(4) angstrom(3) and Z = 4.