Ni(cyclam)]2+ and [Ni(R,S-Me6cyclam)]2+ as Linkers or Counterions In Uranyl–Organic Species with cis- and trans-1,2-Cyclohexanedicarboxylate Ligands

Abstract

The macrocyclic species [Ni(cyclam)]2+ and [Ni(R,S-Me6cyclam)]2+ were used as additional cations in the solvo-hydrothermal synthesis of five uranyl ion complexes with cis- or trans-1,2-cyclohexanedicarboxylic acids (c-1,2-chdcH2 and t-1,2-chdcH2). In the complex [UO2(c-chdc)2Ni(cyclam)(H2O)] (1), dimeric uranyl dicarboxylate subunits are assembled into a two-dimensional (2D) network through axial coordination of NiII to carboxylate groups. Although they involve different isomers, the complexes [(UO2)2(c-chdc)2(c-chdcH)2Ni(cyclam)] (2) and [(UO2)2(t-chdc)2(t-chdcH)2Ni(cyclam)] (3) are very similar, both containing uranyl-based one-dimensional (1D) subunits which are assembled into 2D networks by bridging [Ni(cyclam)]2+ groups. The orientation of the uncoordinated carboxylic group is different in 2 and 3, the layers in 2 being hydrogen bonded to each other through carboxylic acid dimer formation. Using the pure (1R,2R) enantiomer of t-1,2-chdcH2 gives the complex [Ni(cyclam)][(UO2)5(R-t-chdc)3(R-t-chdcH)(O)...