Correlations and differences between uranium(VI) arsonates and phosphonates.

Three new uranium arsonate compounds, UO(2)(C(6)H(5))(2)As(2)O(5)(H(2)O) (UPhAs-1), UO(2)(HO(3)AsC(6)H(4)AsO(3)H)(H(2)O)·H(2)O (UPhAs-2), and UO(2)(HO(3)AsC(6)H(4)NH(2))(2)·H(2)O (UPhAs-3) have been synthesized under mild hydrothermal conditions. UPhAs-1 is constructed from UO(7) pentagonal bipyramids that are chelated by the pyroarsonate moiety, [PhAs(O(2))OAs(O(2))Ph](2-), forming chains of layered uranyl polyhedra. Two of the phenylarsonic acids are condensed in situ to form the fused tetrahedra of the pyroarsonate moiety through a metal-mediated, thermally induced condensation process. The structure of UPhAs-2 consists of UO(7) pentagonal bipyramids that are chelated by phenylenediarsonate ligands, forming one-dimensional chains of uranyl polyhedra. UPhAs-3 consists of a rare UO(6) tetragonally distorted octahedron (D(4h)) that is on a center of symmetry and linked to two pairs of adjacent 4-aminophenylarsonate ligands. This linear chain structure is networked through hydrogen bonds between the lattice water molecules and the -NH(2) moiety. All three of these compounds fluoresce at room temperature, showing characteristic vibronically coupled charge-transfer based emission.