Synthesis and Characterization of a Series of Lanthanide Complexes Constructed from Orotic Acid

The solution reaction of orotic acid (2,6‐dioxo‐1,2,3,6‐tetrahydropyrimidine‐4‐carboxylic acid, H3dtpc) and Ln(NO3)3·6H2O (Ln = La, Ce) or Ln2O3 (Ln = Pr, Nd) yielded five complexes [{Ln(aH2dtpc)2(bH2dtpc)(H2O)4}·H2O]n (Ln = La 1, Ce 3), [La(aH2dtpc)2(cH2dtpc)(H2O)6]·4H2O (2), and [Ln(aH2dtpc)2(OH)(H2O)6]·(H3dtpc)2·7H2O (Ln = Pr 4, Nd 5). Complexes 1 and 3 possess 1D chain structures, 2 is a mononuclear structure, and 4 and 5 are mononuclear complexes that are extended into infinite honeycomb structures through hydrogen bonding interactions. The hydrothermal reaction of orotic acid and Ln2O3 (Ln = La, Nd, Eu, Gd, Er) produced five polymeric complexes [Ln(dHdtpc)(OH)(H2O)]n (Ln = La 6, Nd 7, Eu 8, Gd 9, Er 10), which contain isostructural 3D frameworks with ladder‐like chains formed by LnIII, a µ3‐OH bridge and an orotate spacer. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)