Synthesis and Structure of Metal–Organic Coordination Polymer Based on Lanthanum(III) and Brominated Terphenyldicarboxylic Acid

Abstract

A new metal–organic coordination polymer (MOCP) {La₂(nBrTerPDC)₃DMSO₃} has been synthesized by a solvothermal reaction (in a DMSO/1,4-dioxane solution) between lanthanum(III) nitrate and a brominated terphenyl dicarboxylic acid derivative nBrTerPDC. The structure of this MOCP was solved for the first time by direct methods using X-ray diffraction data. Selected details of the structure solution and parameters of the experiment carried out on the Belok/RSA diffraction beamline at the Kurchatov synchrotron radiation source (λ = 0.7527) are as follows: C₃₆H₃₀Br₉LaO₉S₃, FW 1560.88; space group P\(\bar {3}\), a = b = 26.822(4) Å, c = 8.6710(17) Å, α = β = 90°, γ = 120°, V = 5402.3(19) ų, F(000) = 1476.0, absorption coefficient μ = 4.399 mm^–1, crystal dimensions 0.2 × 0.02 × 0.02 mm, reflection index ranges –21 ≤ h ≤ 32, –32 ≤ k ≤ 32, –10 ≤ l ≤ 9; total reflections 17 717, independent reflections 6459, R_int 0.1072, residual electron density 1.31/–0.62 e/ų. The unit cell contains two structurally unrelated La³⁺ cations. The relatively high factor R₁ = 0.1942 is associated with disorder in the arrangement and degree of occupancy of bromine atoms. This is a consequence of that during the bromination of terphenyl dicarboxylic acid dimethyl ester, bromine attaches to both the central and peripheral aromatic rings of the acid, forming many homologues, presumably mono-, di-, tri-, tetra-, penta-, and hexabromo derivatives, including positional isomers.