Aqueous reactions of U(VI) at high chloride concentrations: Syntheses and structures of new uranyl chloride polymers

The reactions of UO 3 with acidic aqueous chloride solutions resulted in the formation of two new polymeric U(VI) compounds. Single crystals of Cs 2 [(UO 2 ) 3 Cl 2 (IO 3 )(OH)O 2 ].2H 2 O (1) were formed under hydrothermal conditions with HlO 3 and CsCl, and Li(H 2 O) 2 [(UO 2 ) 2 Cl 3 (O)(H 2 O)] (2) was obtained from acidic LiCI solutions under ambient temperature and pressure. Both compounds contain pentagonal bipyramidal coordination of the uranyl dication, UO 2 2+. The structure of 1 consists of infinite [(UO2) 3 Cl 2 (IO 3 )(μ 3 -OH)(μ 3 -O) 2 ] 2 - ribbons that run down the b axis that are formed from edge-sharing pentagonal bipyramidal [UO 6 Cl] and [UO 5 Cl 2 ] units. The Cs + cations separate the chains from one another and form long ionic contacts with terminal oxygen atoms from iodate ligands, uranyl oxygen atoms, water molecules, and chloride anions. In 2, edge-sharing [UO 3 Cl 4 ] and [UO 5 Cl 2 ] units build up tetranuclear [(UO 2 ) 4 (μ-Cl) 6 (μ 3 -O) 2 (H 2 O) 2 ] 2 - anions that are bridged by chloride to form one-dimensional chains. These chains are connected in a complex network of hydrogen bonds and interactions of uranyl oxygen atoms with Li + cations. Crystal data: 1, orthorhombic, space group Pnma, a = 8.2762(4) A, b = 12.4809(6) A, c = 17.1297(8) A. Z = 4: 2. triclinic. snace group P1 a = 8.110(1) A. b = 8.621(1) A. c = 8.740(1) A. Z = 2.