Uranyl Ion-Containing Polymeric Assemblies with cis/trans Isomers of 1,2-, 1,3-, and 1,4-Cyclohexanedicarboxylates, Including a Helical Chain and a 6-Fold-Interpenetrated Framework

Diverse isomers of cyclohexanedicarboxylic acid (chdcH(2)) have been used to synthesize uranyl ion complexes in the presence of various possible counterions and, but for one case, under solvohydrothermal conditions. The cis isomer of 1,2-chdcH(2) gives the complex [UO2(c-1,2-chdc)(H2O)(2)]center dot H2O (1), which crystallizes as an enantiomerically pure helical monoperiodic structure, while partial isomerization of the cis into the trans form yields [PPh4](2)[(UO2)(3)(c-1,2-chdc)(3)(rac-t-1,2-chdc)(H2O)]center dot 2H(2)O (2), a ladderlike monoperiodic assembly. The pure (1R,2R) enantiomer of t-1,2-chdcH(2) gives [UO2(R-t-1,2-chdc)(H2O)] (3) containing a diperiodic assembly of hcb topological type. When reacted at room temperature, its racemic counterpart produces [UO2(rac-t-1,2-chdc)(EtOH)]center dot H2O (4), a diperiodic species with the fes topological type isomorphous to other similar solvates. Using a mixture of the cis and trans isomers of 1,3-chdcH(2) gives [NH4][NBu4][(UO2)(2) (c-1,3-chdc)(2)(t-1,3-chdc)] (5), the first instance of a triperiodic uranyl-containing framework obtained with this ligand. Finally, the complex [H2NMe2](2)[(UO2)(2)(t-1,4-chdc)(3)] (6), containing the trans isomer of 1,4-chdc(2-), crystallizes as a triperiodic framework with the topology and displays 6-fold-interpenetration, the highest degree found up to now in a uranyl ion complex. These results are discussed together with previous ones obtained with this highly versatile family of cyclohexanedicarboxylate ligands.