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

A new lanthanum complex, (H3O)(2)[La(C7H3NO5)(2)(H2O)(2)](2)center dot 3(H2O) or (H3O)(2)[La(HChel)(2)(H2O)(2)](2)center dot 3(H2O) 1 (H(3)Chel = 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 I crystallizes in triclinic, space group P (1) over bar with a = 9.6939(19), b = 10.176(2), c = 11.502(2) angstrom, alpha = 111.52(3), beta = 93.74(3), gamma = 103.33(3)degrees, V = 1013.0(3) angstrom(3), D-c = 1.912 g/cm(3), Z = 1, M-r = 1166.40, mu = 2.188 mm(-1), lambda(MoK alpha) = 0.71073 angstrom and F(000) = 574. The final R = 0.0342 and wR = 0.0737 for 4080 observed reflections with I > 2 sigma(I), and R = 0.0429 and wR = 0.0772 for all data. Compound I contains two lanthanum ions, four chelidamic acid ligands, four coordinated water molecules, two hydroniums, and three discrete water molecules. The La-III 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.