Uranyl-Organic Assemblies with Acetate-Bearing Phenyl- and Cyclohexyl-Based Ligands

Six novel complexes formed under hydrothermal conditions by uranyl ions with three ligands comprising a rigid phenyl- or cyclohexyl-containing platform, and two to four acetate arms have been obtained. 1,3,5-Benzenetriacetic acid (H(3)BTA) yielded the complex [NMe(4)][UO(2)(BTA)]center dot H(2)O (1), in which the structure-directing counterion induces a two-dimensional, bilayer-type structure different from that previously reported, with both the tris-chelating ligand and the metal ion as trigonal nodes. Two complexes were obtained with 1,2-phenylenedioxydiacetic acid (H(2)PDDA), [UO(2)(PDDA)(H(2)O)] (2) and [H(2)DABCO][(UO(2))(2)(PDDA)3]center dot 1.5H(2)O (3). Complex 2 is a simple, ribbon-like, one-dimensional polymer, while 3 is a nanotubular assembly built around the hydrogen-bonded, structure-directing counterions. Three complexes were obtained with trans-1,2-diaminocyclohexane-N,N,N ',N '-tetraacetic acid (H(4)DCTA), a polyaminopolycarboxylic acid, with different bases, [UO(2)(H(2)DCTA)(H(2)O)(2)]center dot H(2)O(4), [UO(2)(H(2)DCTA)(H(2)O)]center dot 1.5H(2)O (5), and [UO(2)Na(HDCTA)(H(2)O)] (6). The nitrogen atoms are not coordinated, both of them (4) or only one (5 and 6) being protonated, and the carboxylic/ate groups are monodentate, except for one chelating in 6 and one nonbonding in 4. These differences in bonding result in various assemblies, one-dimensional in 4 and two-dimensional in Sand 6. The layers in 5 are strongly corrugated, with the cyclohexyl groups pointing on either side, and their packing displays oval-shaped channels, while the layers in 6 are planar, with the cyclohexyl groups located on one side, and further assembled into dimeric units by the disordered sodium ions. These are the first crystal structures of actinide ion complexes with both H(2)PDDA and H(4)DCTA.