Structural chemistry of mixed-ligand fluoride complexes of uranyl

Abstract

The crystal structures of mixed-ligand sulfato-, selenato-, phosphato-, arsenato-, and chromato-fluoride complexes of uranyl and of mixed-ligand carboxylato-fluoride and mixed-ligand fluoride complexes with neutral donor ligands studied by the single-crystal X-ray diffraction method were systematized and discussed. The crystal chemical features of the structures of the mixed-ligand fluoride complexes of uranyl were determined: the coordination polyhedron of the hexavalent uranium atom in the structures of the mixed-ligand fluoride complexes of uranyl (except for three hexagonal-bipyramidal complexes) has a pentagonal-bipyramidal structure: the oxygen atoms of the uranyl group are located on the vertical axis of the pentagonal bipyramid, perpendicular to the equatorial plane in which five atoms are located. In dimeric and polymeric chains of mixed-ligand fluoride complexes of uranyl (with the exception of one compound in which the common bridge in the dimer complex is oxygen atoms), the uranyl units are linked via fluoride bridges. Inorganic and organic ligands, which contained O-donor atoms, combine dimers and polymer chains into layers and three-dimensional formation.