Layered lanthanum complex with 3-nitrophthalic acid assembled via hydrogen bonds synthesis, structure and characterization of [LaL(HL)(H₂O) ₃]₂ · 2H₂O (H₂L = 3-NO ₂C₆H₃(CO₂H)₂)

A new dinuclear centrosymmetric complex [LaL(HL)(H₂O) ₃]₂·2H₂O (H₂L = 3-nitrophthalic 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) Å, α = 100.93(3), = 90.81(3), γ = 104.56(3)°, V = 1049.8(4) ų, Z = 1, μ = 2.125 mm ¹, D_c 1.994 g/cm³, R = 0.0259 and wR = 0.0679. Two 3-nitrophthalates(2-) coordinate with the La³⁺ ions in a bridging mode, and two monohydrogen-3-nitrophthates(1-) and three waters in terminal ways, respectively. Each La³⁺ ion is ninecoordinated 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.