Synthesis and Crystal Structure of a Lanthanum(III) Complex with Chelidamic Acid

A new lanthanum complex,(H3O)2[La(C7H3NO5)2(H2O)2]2·3(H2O) or (H3O)2[La(HChel)2(H2O)2]2·3(H2O) 1 (H3Chel=4-hydroxypyridine-2,6-dicarboxylic(chelidamic) acid),has been prepared by the hydrothermal reaction,and its crystal structure was determined based on single-crystal diffraction data. Compound 1 crystallizes in triclinic,space group P1 with a=9.6939(19),b=10.176(2),c=11.502(2),α=111.52(3),β=93.74(3),γ=103.33(3)o,V=1013.0(3) 3,Dc=1.912 g/cm3,Z=1,Mr=1166.40,μ=2.188 mm-1,λ(MoKα)=0.71073  and F(000)=574. The final R=0.0342 and wR=0.0737 for 4080 observed reflections with I 2σ(I),and R=0.0429 and wR=0.0772 for all data. Compound 1 contains two lanthanum ions,four chelidamic acid ligands,four coordinated water molecules,two hydroniums,and three discrete water molecules. The LaIII atom is ten-coordinated by four oxygen and two nitrogen atoms from two tridentate chelating chelidamic acid ligands,two carboxylic oxygen atoms from an adjacent chelidamic acid ligand and two coordinated water molecules,leading to a distorted dodecahedral geometry. A three-dimensional network is formed by H-bonds.