Layered Lanthanum Complex with 3-Nitrophthalic Acid Assembled via Hydrogen Bonds—Synthesis, Structure and Characterization of [LaL(HL)(H_2O)_3]_2·2H_2O (H_2L = 3-NO_2C_6H_3(CO_2H)_2)

摘要

A new dinuclear centrosymmetric complex [LaL(HL)(H_2O)_3]_2·2H_2O (H_2L = 3-nitro-phthalic acid, NPA) was synthesized in water/ethanol solution and characterized by X-ray diffraction, IR spectrum and TGA-DTA. The complex crystallizes in triclinic system, space group P1 with a = 8.1549(16), b = 8.8856(18), c = 15.277(3) A, α= 100.93(3), β= 90.81(3), γ= 104.56(3)°, V = 1049.8(4) A~3, Z = 1, μ = 2.125 mm~(-1), D_c = 1.994 g/cm~3, R = 0.0259 and wR = 0.0679. Two 3-nitrophthalates(2-) coordinate with the La~(3+) ions in a bridging mode, and two monohydrogen-3-nitrophthates(1-) and three waters in terminal ways, respectively. Each La~(3+) ion is nine-coordinated to exhibit a distorted tricapped trigonal prism coordination polyhedron. Both the coordinated and crystal waters are involved in the inter- and intramolecular hydrogen bonds. The dinuclear units are linked into a 2D network structure in the ab plane via intermolecular hydrogen bonds along the axes a and b. Two crystal waters fill each rhombic pore of the network. The networks are further packed along the c axis forming a layered supramolecular structure through the C-H…O weak forces between the adjacent sheets. TGA analysis shows the complex undergoes the loss of waters of crystallization and coordination and the decomposition of ligands sequentially.