The roles of H-bonding, π-stacking, and antiparallel CO ⋯ CO interactions in the formation of a new Gd(III) coordination polymer based on pyridine-2,6-dicarboxylic acid.

This study reports the synthesis of a new catenane Gd(III) complex using pyridine-2,6-dicarboxylic acid (H 2 pydc) as ligand. The structure of [Gd(pydc)(Hpydc)(H 2 O) 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 H 2 pydc 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 (pydc 2 − ) forms of the ligand counterbalance the Gd 3 + 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”. [ABSTRACT FROM AUTHOR]