Uranyl Complexes as Scaffolding or Spacers for Cucurbit[6]uril Molecules in Homo- and Heterometallic Species, Including a Novel Uranyl-Lanthanide Complex
Résumé
Reaction of uranyl nitrate with cucurbit[6]uril (CB6) and carboxylic or sulfonic acid ligands under hydrothermal conditions and in the presence of additional metal cations (K I or Ce III) or co-solvents provided four complexes which were crystallographically characterized. [(UO2)2K2(CB6)(adc)2(NO3)2(H2O)2]⋅5H2O (1), where H2adc is 1,3-adamantanedicarboxylic acid, crystallizes in the form of a central K2(CB6) 2+ column surrounded by two one-dimensional (1D) polymeric UO2(adc)(NO3) – chains attached to the column by nitrate bridges, with a perfect match of the repeat lengths in the two subunits. The longer 1,3-adamantanediacetic acid (H2adac) gives the complex [(UO2)2(adac)2(HCOOH)2]⋅CB6⋅6H2O (2) in which the 1D uranyl-containing polymer and columns of CB6 molecules form a layered arrangement held by weak CH⋅⋅⋅O hydrogen bonds. The complex formed with the di-potassium salt of methanedisulfonic acid (K2mds), [(UO2)2K2(CB6)(mds)2(OH)2(H2O)8]⋅4H2O (3), is a 1D polymer in which K2(CB6) 2+ units are connected to one another by doubly hydroxide-bridged uranyl dimers in which the disulfonates are terminal, chelating ligands; connection between the two subunits is solely through potassium oxo-bonding to uranyl. The complex [(UO2)2Ce2(CB6)(C2O4)3(NO3)4(H2O)6]⋅2H2O (4) is a 1D polymer containing bridging oxalate ligands formed in situ, in which CB6 is coordinated to the lanthanide cations only; one nitrate and one water ligands hydrogen bonded to each other are included in the CB6 cavity, with the possible occurrence of interactions between nitrate oxygen atoms and ureido carbon atoms.
Domaines
Matériaux
Origine : Fichiers produits par l'(les) auteur(s)
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