Solvothermal Synthesis and Crystal Structure of Uranyl Complexes with 1,1‐Cyclobutanedicarboxylic and (1R,3S)‐(+)‐Camphoric Acids – Novel Chiral Uranyl‐Organic Frameworks

Reaction of the 1,1‐cyclobutanedicarboxylic (H2L1) or (1R,3S)‐(+)‐camphoric (H2L2) acids with uranyl nitrate under solvothermal conditions gives novel uranyl‐organic assemblages. The complex [Hpy]2[UO2L1(NO3)]2 (1), obtained in pyridine, is a dimeric, dinuclear species in which the closeness of the two carboxylate groups prevents the formation of a more extended architecture. The chiral complexes [UO2L2(py)2]·py (2) and [UO2L2MeOH]·MeOH (3), obtained with the enantiopure, divergent camphorate ligand in either pyridine (2) or methanol/water (3), are comprised of zigzag chains defining channels and a microporous assemblage or of undulated sheets based on tessellated 8‐ and 32‐membered rings, respectively. Apart from a zinc(II) complex previously described, compounds 2 and 3 are the only examples of metal complexes with camphoric acid crystallographically characterized. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)