Synthesis, structural characterization and computational studies of...

Coordination polymers are constructed from two basic components, namely metal ions, or metal-ion clusters, and bridging organic ligands. Their structures may also contain other auxiliary components, such as blocking ligands, counter-ions and nonbonding guest or template molecules. The choice or design of a suitable linker is essential. The new title zinc(II) coordination polymer, [Zn(C₅H₅NO₃P)Cl]_n, has been hydrothermally synthesized and structurally characterized by single-crystal X-ray diffraction and vibrational spectroscopy (FT-IR and FT-Raman). Additionally, computational methods have been applied to derive quantitative information about interactions present in the solid state. The compound crystallizes in the monoclinic space group C2/c. The four-coordinated Zn^II cation is in a distorted tetrahedral environment, formed by three phosphonate O atoms from three different (pyridin-1-ium-3-yl)phosphonate ligands and one chloride anion. The Zn^II ions are extended by phosphonate ligands to generate a ladder chain along the [001] direction. Adjacent ladders are held together via N-H...O hydrogen bonds and offset face-to-face π-π stacking interactions, forming a three-dimensional supramolecular network with channels. As calculated, the interaction energy between the neighbouring ladders is -115.2 kJ mol^-1. In turn, the cohesive energy evaluated per asymmetric unit-equivalent fragment of a polymeric chain in the crystal structure is -205.4 kJ mol^-1. This latter value reflects the numerous hydrogen bonds stabilizing the three-dimensional packing of the coordination chains.