This study reports the synthesis of a new catenane Gd(III) complex using pyridine-2,6-dicarboxylic acid (H2pydc) as ligand. The structure of [Gd(pydc)(Hpydc)(H2O)2]n (1) was characterized by IR spectroscopy, X-ray diffraction methods and the elemental analysis to check the purity of the compound. On the basis of crystallographic data, compound 1 contains a Gd(III) metal center that is coordinated to seven oxygen atoms of two tridentate and one monodentate H2pydc ligands and two coordinated water molecules. Other lanthanoid complexes involving this ligand are available in the literature; however, this is the first example where a combination of monoanionic (Hpydc−) and dianionic (pydc2 −) forms of the ligand counterbalance the Gd3+ metal center. The intermolecular interactions in this novel system consist of different kinds of H-bonding and π-stacking interactions in addition to antiparallel CO ⋯ CO interactions which have been analyzed using DFT calculations and the Bader's theory of “atoms in molecules”.

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