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, H 3 dtpc) and Ln(NO 3 ) 3 ·6H 2 O (Ln = La, Ce) or Ln 2 O 3 (Ln = Pr, Nd) yielded five complexes [{Ln( a H 2 dtpc) 2 ( b H 2 dtpc)(H 2 O) 4 }·H 2 O] n (Ln = La 1 , Ce 3 ), [La( a H 2 dtpc) 2 ( c H 2 dtpc)(H 2 O) 6 ]·4H 2 O ( 2 ), and [Ln( a H 2 dtpc) 2 (OH)(H 2 O) 6 ]·(H 3 dtpc) 2 ·7H 2 O (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 Ln 2 O 3 (Ln = La, Nd, Eu, Gd, Er) produced five polymeric complexes [Ln( d Hdtpc)(OH)(H 2 O)] n (Ln = La 6 , Nd 7 , Eu 8 , Gd 9 , Er 10 ), which contain isostructural 3D frameworks with ladder‐like chains formed by Ln III , a µ 3 ‐OH bridge and an orotate spacer. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)