Synthesis and structure of the two-dimensional coordination networks [Ln(PDC)(N-HPDC)]∞ (PDC = pyridine-3,4-dicarboxylate, Ln = La, Ce, Pr)

The title compounds, [Ln(PDC)(HPDC)]∞ (H2PDC = pyridine-3,4-dicarboxylic acid, Ln = La, Ce, Pr), have been prepared and have been characterised by IR, MS, TGA, X-ray crystallography and powder diffraction. These isostructural complexes display both bridging and chelating carboxylate binding modes including a highly unusual chelation in which both carboxylate substituents bind to the same Pr atom, imparting chirality around the metal despite the non-chiral crystal setting. This system represents the first fully characterised metal complex containing the N-protonated ligand derivative (N-HPDC−). A polymorph of the ligand precursor, pyridine-3,4-dicarboxylic acid is also reported.

Graphical abstractNine coordination of the lanthanoid invloves μ4-η1:η1:η2:η1(N) coordination of a PDC2− ligand and μ-η2:η2 coordination of the N-protonated ligand N-HDPC−.Figure optionsDownload full-size imageDownload as PowerPoint slide